Thinking of going from Automatic to 4-Speed

don't use the truck tranny. Its a heavy duty, granny low sort of thing. You need a 833 period. The shifter mount is on the very back of the tail shaft housing. The tail shaft housing is specific to an A and F body. 66 A body can be a donor to 67-69 cuda but no earlier than 66 as 65 and earlier have the wierd trunnion thing going on at the rear of the trans where drive shaft connects.

There are lots of little parts to chase as that what I've been doing for about 18 months (I haven't been diligent though). I lack the clutch linkage and then I will have a complete setup.

My 67 cuda was an auto that I'm converting. I did a decent job on welding the hump in by mounting the empty block and trans into the chassis and then centered up the shifter hole of the hump with the shifter mounted up. No guessing if its in the right spot or not. The hump doesn't absolutely fit into one spot.

It would be best to find a donor car with all needed stuff as the little parts are the pain in the a$$. But finding a complete car is a fat chance thing as well. Shifters are pretty easy to find. I see Hurst non-console type A body shifters with rods/swivels/ and handle all day long on Ebay. The clutch stuff is where it gets difficult. Bell housing is particular to whether you have a small or big block. You said you have a 360 so you need a bell with a bolt hole at the 12 noon position on the back of the block. Big blocks don't have a hole there (thats what I have for my 400).