What others have recommended....I went to my local U pull-it and harvested the front drive off of a 1995-1997 C1500 and mounted on my square body 350. Things you will need to do:
1. Grab both aluminum brackets and the bolts
2. Grab the power steering pump
3. You will need a reverse rotation water pump. I used AC Delco 252-664
4. Purchase CPP 500IOA fittings kit. You will use the one fitting to connect the 1995 HP Power Steering Line to the 1979 Steering Box
5. The Power Steering/AC Compressor bracket will bolt the the 350 SBC.
6. The alternator/idler/tensioner pulley will only match one bolt hole on the passenger side head. I made an L bracket from aluminum angle which I bolted to the back of the bracket. I put a stud on the front passenger side manifold bolt. Torqued a nut to that for the manifold, then bolt the L brack to the stud.
7. Running a mechanical fan for that setup.