I put a NV4500 in my 71 4x4, it all should be the same from the motor to the transmission. I used a GM bellhousing with hydraulic clutch. I think the 4500 has two bolt patterns, so make sure you get the correct bellhousing for the transmission.
Advance Adapter also builds a bellhousing that uses the stock mechanical clutch in your pickup. The clutch was quite easy to use, just a little bit of planning to get the clutch master mounted correctly. I can't speak to the other issues Huck mentioned, but what he mentioned sounds like it would be the same for the 4500.
LJ