Not much particular to that family of trucks really stands out - they're pretty solid trucks. I personally would aim for a 350ci engine versus a 305 (personal preference), but other than that I can't really think of anything. That, together with a TH350 transmission (or a manual) and you've got a pretty reliable package.
I've never heard of a 2WD frame cracking at the steering box.
Check the ball joints (but I'd check that on any truck).
My first truck was an '86 C-10. I traded it for a '71 C-10 in college.