One major problem with a POD this late is that there are already several fronts on which the Soviet Bloc was falling behind in this time period.
Take China, for instance. By this point in the 1960's, the Sino-Soviet Split had resulted in yet further sectarianism amongst the Revolutionary Left, and any rapprochement was made highly improbable thanks to the Cultural Revolution. Ultimately, Nixon's visit to China, followed by Deng Xiaoping's re-integration of the country into the capitalist world as a sweatshop platform, gave capitalism a massive counterwieght to the Soviets on the Eurasian mainland. Even if the PRC somehow manages to get out of the Cultural Revolution earlier, the Mao-led hatred of Soviet "Revisionists" is unlikely to die out quickly enough for a new friendship between the two nations to emerge. Nonetheless, if China somehow avoids falling into the capitalist camp, that'll deprive Western industries of a major place to outsource their manufacturing.
Within the Soviet Union and the other Warsaw Pact nations, there needs to be plenty of divergence from OTL on several fronts. Butterflying away the Prague Spring, or somehow preventing the Soviet leadership from sending in the tanks, will do wonders for the Soviets' reputation vis a viś Eastern Europe (as well as the Western part). In the Kremlin itself, it's absolutely necessary to reshuffle the make-up of the Politburo, starting first and foremost with getting Brezhnev into an early retirement. IMO Alexei Kosygin would make for a good successor to a disgraced (or deceased, if an assassiation is what removes him) Brezhnev, or perhaps a less hawk-minded Yuri Andropov (by this I point out that Andropov was one of the chief proponents of crushing the Prague Spring).
Still, whichever leadership emerges in Moscow, it'll have to have ambitions both abroad as well as at home. Besides greater support for Revolutionaries in the Global South, the Soviet economy will have to get re-energized during this time period. Greater investment should be directed towards the Central Asian republics, to exploit their oil and natural gas reserves as well as provide better infrastructure. In the planning realm, getting a technological/information revolution going is definitely a must. Programs directing state enterprises to standardize and integrate their computing material can pave the way for a nationwide computer network (which can also extend to the other Soviet allied states) that'll allow for more effective communication amongst planners. In time, such a network - a "Communet" if you will - can also become more readily available to everyday Soviet and Warsaw Pact workers, provided that other areas are further improved upon.*
--Areas such as gaining more and more allies beyond the Iron Curtain, in Asia, the Middle East, Africa, even Western Europe and Latin America. For East Asia: assuming that the POD is 1967 - yes, by this point Indonesia is almost certainly a lost cause for the time being, as their Communist party (before 1965, the third largest) was decimated by Suharto. Outside of Indochina, I guess the Soviet Bloc can redirect their efforts toward supporting anti-Marcos rebels in the Phillipines and possibly making inroads to the other mainland Southeast Asian countries such as Burma. Also, if pro-Soviet North Korean officials somehow overthrow Kim Il-Sung (I guess while the Dear Leader is on a visit to Moscow), the DPRK together with Vietnam can take a more proactive role in supporting revolutionaries throughout the region (much like Cuba). As for China, see my first paragraph.
South Asia is probably the easiest place for the Soviet Bloc to spread its influence. IOTL, India had pretty good relations w/ the Soviet Union, culminating under Indira Gandhi's administration. If the local communist parties somehow manage to overcome their own factionalism (and if the Naxalite rebellion is somehow resolved early on), and manage to drag India's political culture further leftward, it might be possible for India to even become an observer state of COMECON.
In the Middle East, the best places for Pro-Soviet forces to emerge besides South Yemen are Syria and Iraq, though for both cases the Husseins and Al-Assads preferably shouldn't be involved. Iran
might be an opportunity if the Soviets are willing to potentially pull another Cuba in terms of ratcheting up tensions w/ the West. But for the Tudeh Party to gain more traction and not be seen as merely a replacement of American-backed stooges for Soviet-backed pawns? That'll be quite an undertaking. But if that major gamble succeeds, the West will have to double down on its support for the Saudis and the other Gulf Monarchies, which BTW will be constantly paranoid about their oppressed Shi'ite minorities (esp. Bahrain).
For greater Soviet Bloc success in Africa, prevent Mengistu from taking power in post-Imperial Ethiopia. Soviet goodwill toward the continent was severely tarnished by the legacy of famine, civil war and terror under the Derg regime. Better for there to be focus on helping comrades in Angola and Mozambique fight against the Apartheid regime, as well as economic aid which provides a viable alternative to the World Bank/IMF's structural adjustments.
Western Europe has a few opportunities for Soviet advancement, albeit ones that'll surely ratchet up tensions. Portugal and Greece are the most likely candidates (as depicted in Drew's
Fear, Loathing, and Gumbo), but another place for revolution to come about is possibly France in May 1968. Assuming that the General Strike goes unresolved and escalates into a genuine threat to the French state, there's a plethora of possible outcomes which I'll not get into detail about.
And finally, the New World. Honestly, even with a POD that has Che Guevara inheriting Fidel's luck at avoiding assassination, I don't see much opportunity for Soviet influence to spread here (at least during the 70's and '80's) beyond Cuba and Central America. I'd guess that in a Soviet Survival scenario (where the Warsaw Pact is alive and well going into the 90's), Chavez
might emerge as an ally should he manage to come to power, but butterflies from the POD might lead to him (and his fellow travelers in the Venezuelan military) on to different paths. And he need not be a dictator either, because by this point (the 1990's/2000's) I'd imagine that the hypthetically more successful Soviet bloc will have loosened its ideological rigidity in accepting more and more allies.
-BTW, if this post comes across as incoherent in any way, it's because I typed it up on my mobile (took about 2 hours to type up at my rate.
*the man to lead this task would be Viktor Glushkov, the main proponent of Integrating computer networks into economic planning. Further details are mentioned in the essay
InterNyet.