904 internals

I'd personally go with the alto red clutches & kolene steels for the drums. I did new bushings, rings, thrust washers in mine as well. Transgo TF-2 or TF-3 for the shift kit depending on whether you want an auto shift or full manual. Solid kickdown band is typically preferred as is either a 3.8 or 4.2 lever.

Also the ATSG manual is a help for the build.