The best way would be to put v8 parts in it. It has to be the correct year range and or get pump with both drums out of a v8 unit so you don't have to worry about mixing and matching stuff.

A 4 clutch rear drum- 4 will be fine
A 4 clutch front drum- you can use forward (rear clutch) discs to accommodate 5 discs with little machining required.

Good luck!