I want to upgrade gearbox 3 speed th400 just wont do it for me. And i can just replace th400 with 4l60e without doing the swap

Hello fellow g vanners. I have 89 g30 starcraft with a 6.2 and th400. I also aquired 93 g30 starcraft with a 6.2 and 4l60 for parts since the body is too rusted away. I would like to take engine and transmission from 93 and put it to 89. As far the engine and transmission itself it should be pretty ...