If power steering is a must, you need to stay with the 72-93 truck.
72 has some one of things going on,and you wanted to stay under 1980, so a 73-79 would be the choice.

Personally, I prefer the 49-59 trucks, but someone would have done a lot of work to have power steering on those years. In my case, that someone would have been me. I could do a really nice driver truck for under $10,000, but there is a difference between a really nice driver, and a really nice truck. Really nice show trucks are not much fun to drive. Gene