I was lucky to find oversized pistons for my 4g32. Spent a lot of time trying to cross reference different 4g32 models, some were close and the pistons I got matched.
Search my posts of you want to hear the story with documents and all,might save you some time. The moral of the story, i rebuilt mine in the last year about, main bearings and rod bearings were easy to come by as well as valves and gasket kit, timing belt (not chain), belts for the governor and alternator (i have the 742b), the sticking point was the pistons. Found them on ebay by luck more than skill.
There are several versions of the 4g32 that were made, so finding a car with it didn't really help.
Some had said parts for the 4g63 were easier to get and recommended going that route.
Good luck, I spent about 6 months doing research on and off, got wrong valves at one point, wrong pistons, wrong timimg belt... Eventually it came together, I'm still not sure how, but luck was a big part.
