Finding a way to discredit the Congress Party sometime between 1947-1977 is a good start for India to become an economic hub. As for Pakistan, maybe if it was bigger (Maybe the Pakistan-Afghanistan confederation happens in the 1950s, and Pakistan keeps Bangladesh, has the Muslim majority areas of Burma and the Muslim parts of Indian Punjab) it could decentralize and coups would be harder to pull off. Remember South Korea based its economic model off of Pakistan's.
Having both Pakistan and India not be enemies, probably if Kashmir was partitioned, will make this easier as they will both be US allies and will be more open to investment.