I've been looking for capitalist dictatorships in the cold war era to use as a model here; not a lot of luck:
The RoC's situation changes drastically if we assume it keeps the mainland, so it's not totally applicable. We can't assume that a full nationalist China will grow in the same way that Taiwan did.
In Ethiopia, Brief modernization in the 1950s followed by stagnation starting around 1960 leads to a communist coup d'etat. However, Ethiopia was a deeply monarchist country during this period, and Selassie's succession was also a factor. Qing has by this time been dead and buried for decades, so it's not an applicable model.
Liberia's economy never diversified, so the civil war completely ruined it. In a country the size of China, that's not really a factor here. Additionally, the civil war itself was due to ethnic tensions that don't come into play.
Apartheid South Africa from 1948-1985 was an authoritarian republic much like the RoC, with an established class system, albeit one based on race. It could be tempting to make a blacks=rurals comparison given the PRC's Hukou system, but the active suppression from Apartheid goes far beyond Hukou; any comparison here would be useless.
Any use a comparison with Afghanistan might have was obliterated in 1979; Soviet Russia is highly unlikely to invade China even if it was to support a coup. The logistics alone would murder them.
Indonesia seems promising. Sukarno was a figurehead to the military until 1959, and was deposed in 1967; Suharto was closely aligned to the US. Economic growth was maintained from 1967-81 and from 1988-97; the period from 1981-1988 showed anemic growth due to declining oil revenues and inflation; the GDP per capita, however, exceeded that of China, in contrast to before. The corruption endemic to Suharto's regime was masked by a great deal of economic growth. Eventually, the asian financial crisis hit and Indonesia was hit hard. Indonesia was also involved in border wars, annexation attempts, and insurgencies, as Nationalist China would.
If we use Indonesia as an example, there would probably be a communist purge immediately after the CPC is defeated, followed by the dismantling of the warlords. China's economy would grow from $52 per capita to some $340 by 1965, a feat not reached IOTL until 1977. Assuming that this China has diversified its economy more than OTL Indonesia's (not a difficult task), then the anemic growth experienced by Indonesia after 10 years would be boosted considerably. However, that may also delay some much-needed reforms. When the oil crises occur in the '70s, it causes massive amounts of inflation as the inept financial sector crumbles. Per capita GDP falls from ~$1000 to $500 at some point during the decade. Given prices at the time, China's GDP would fall from second place to fourth place (after West Germany). This combined with Chiang Kai-shek's death around that time causes large-scale unrest that eventually gives way to a democratic revolution. It takes a full decade to reach the economic level it once did, but grows tremendously; it doesn't become the second-largest economy again until Japan's GDP tumbles in 1996 (assuming the "lost decade" isn't butterflied). China becomes the largest economy around 2004; in 2012 its GDP per capita is ~$11,000.
Imperial Iran is a tempting example; an autocracy buoyed by western interests, and a target of colonialism since the prior century that caused the downfall of its previous government. However, the reign of Reza Shah is probably a closer example to Chiang Kai-shek's China, and his forced abdication during world war 2 makes this a rather poor example, unless world war 3 begins in the late 1960s, the US loses, and the Soviet Bloc attempts to invade China. If this happens, the Iranian model would predict that China would be controlled by the USSR until the early '00s, when a deeply reactionary religious-nationalist revolution occurs. In 2012 the Confucian/Taoist/Buddhist/Whatever Republic of China is the third-largest economy after the Soviet Union and Communist India. This would be, of course, very silly and probably ASB.
South Korea seems the obvious choice for many reasons; it parallelled Taiwan for much of its history and the Korean people were in roughly the same position as the Chinese. Syngman Rhee and Chiang Kai-shek invite comparisons as well. However, it bears mentioning that economy of South Korea and the economy of China were not at the exact same level in the 1950s. Japanese investment during the colonial era and American investment in rebuilding after the Korean War fueled much of it, which wouldn't be possible to the same degree in a country as large as China.
The RoK and RoC both carried out large communist purges in the prewar era. If the GMD stays in power, these would probably be expanded massively. Without the mainland under communist control, the GMD won't have a proper excuse to postpone elections; on the other hand, Chiang Kai-shek was more competent than Rhee; he could hold onto power well into the 1970s. He also had greater control over the military, making the regime more stable. In 1985, it's become the 3rd largest economy, passing the USSR. During this time, it liberalizes. In the '90s, an alt-East Asian Financial Crisis causes the economy to shrink drastically, though it quickly rebounds. China's economy slightly underperforms in terms of GDP when compared to OTL, but has a much larger middle class and a more developed technology sector.
Pakistan has been mentioned as a potential model; it certainly has a similar history with martial law and military dictatorships. If Chiang follows the example of Ayub Khan, then there would be a much widened gap between rich and poor. However, Chiang did not align himself with free-market economics, so it's unlikely that he would follow that path. This does not preclude him being replaced, however. In the 1970s, rising tensions with Russia and a failed attempt at reunification leads to the secession of one or more provinces, possibly Tibet, the Muslim West, tribal Yunnan, or Manchuria if it's not already communist; these are supported by another country, possibly India or Russia. This causes economic stagnation. Increasing ethnic tensions in the fringes are met with military force, possibly in the Cantonese south. Widespread nationalizing reforms cause even more economic stagnation, which results in popular unrest and a military coup. It slightly outperforms the PRC in the '80s and '90s, but rising extremism and a regional financial crisis seriously damaged its economy; in 2001 its GDP falls behind Brazil; in 2012 it's stuck in 11th place just ahead of India, while the poorer regions such as Yunnan and Xinjiang are the site of long-standing insurgencies.
One country often overlooked in its similarity to China is the Congo. Geographically, both countries are large and have a great deal of natural resources. In addition, both countries had autocrats installed and large numbers of provincial warlords. Congo and China actually had a similar GDP per capita during the late 1970s, when Deng Xiaoping launched economic reforms that propelled China's growth while rebellions and political mismanagement in the Congo caused its decline. Supposing that whoever takes over the GMD from Chiang sets up a charismatic regime, makes his party a quasi-religious institution, and centralizes the country to an extreme degree while taking most of the revenue for his own gain, culminating in a protracted civil war, China would certainly end up as a third-world backwater. However, I think it would be unlikely for China.
The Philippines and Thailand may also be good models, but I'm tired.