Back during EU4's development, there was a big discussion on having a set of variable tech group levels. The basic suggestion was that there be three major levels in each technology group representing the development of tech throughout the time period. Certain conditions could make you advance to the next level, with Europeans more likely to do this thanks to their starting point. The idea couldn't be implemented in EU3's system, and the devs didn't use it. I'm not sure if it could be modded into EU4 as it currently is, but it could be worth a try.
Tech levels would be stuff like:
Western Medieval (120% costs), Western Renaissance (100% costs), Western Enlightened (80% costs)
Classical New World (200% costs), Post-Contact New World (120% costs), Westernized New World (100% costs), Enlightened New World (80% costs)
Early Modern Muslim (100% costs), Enlightened Muslim (80% costs)
Oriental Chinese (100% costs), Enlightened Chinese (80% costs)
This system would allow most of Europe to start off behind China and the Muslim world (as they were historically), catch up with them after 50-100 years, and then pull ahead in the last 150 years of the game. Following the historic route.