None of the parts for the 3 speed will swap except the flywheel/clutch, Driveshaft and clutch linkage.
If the bellhousing has the dual bolt patterns then you can use it. My slant six housing did not, but I am pretty sure the V8 bellhousings are all dual pattern.

Shifter, shift linkage are different.

You can get a shifter from a later model truck and change the rods & Handle. Late model transmissions may not have the rear mount holes drilled in the extension housing of the transmission but the shifter will fit.

I think the plate that bolts between the shifter and the transmission extension will have to come from an E body or a 71 and later B body. The truck adapter will be too high I believe. Easy to fabricate from Thick aluminum plate.

As for the Piston grip on a 3 speed I did not try to make it work. The 3 speed has 3 vertical bolts holding the handle to the shifter. The 4 speed has 2 horizontal bolts. You may be able to make an adapter, cut and weld a plate to the bottom of the pistol grip or possibly combine parts of the 2 shifters to make it work. I just swapped a 4 speed into mine.

Brewers is a good place for the parts you may need or advice on what to get.