I had a 63 C20 with an Olds 350 and a power steering unit from a 70 Chevy truck. The problem is particularly if you have a six is finding all the pulleys and brackets. If you find a motor with the power steering, you need all the pulleys, water pump, harmonic balance (unless it looks exactly like yours), power steering pump pulley and the brackets.
Larry
68 C20 327/465 daily driver
63 C20 292/420 Camper truck
65 C10 ? /powerglide Custom Cab AC,PB,PS,$flashe
70 C10 250/3spd org/Gauge dash,Wood bed, 4Sale$1300

I don't own a vehicle that isn't old enough to drink.