May need advice on 727 build

Next Question , I have two Transmissions stripped down laid out on the bench seperately so I do not mix parts up , one is an Early pre 71 and the other after 71, I know its the 71 i need to use to upgrade, I know some parts are definetly not interchangable especially the oil pump and support, But what about the Clutch drums as I know the early one has a four clutch drum and the later has only three, are there any other later parts interchangable So I can select the best from each before I select new parts for the Build Thanx