dynasour,
My 50 5 winder was also a 3 speed years ago but the PO changed it to 4 on the floor. Best thing that ever happened. Wife says it a lot more manly like. Hopefully someone with tons of resources will be able to help you out. Never done it, don't you only need:

1. 4 speed tranny with shifter (same length as a 3 speedo ?)
2. Fancy shift knob (maybe a deactivated hand grenade).
3. Floor tranny plate.

What else is there ? What is great is being able to eliminate all that column linkage.

Cheers

Craig

My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear
My truck ....... Respect The Rust
If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.