They aren't hard to rebuild and the stock stuff can handle a decent power level.
Northern auto for a rebuild kit, wit or some others for bands, get a bolt in sprag if you want it and the TF book.
There is a series on youtube from a shop in Australia that does a performancce rebuild on a 727. Good resource.
https://www.youtube.com/watch?v=xzJhCBZ1wMYLots of BS black magic regarding building mopar transmissions. They are probably the easiest to get done. Save money on the trans rebuild and spend that money on a great converter that will REALLY make a difference in how the car runs.
