May be picking up a 51 GMC

[tantrumpipeline]

Just replied to a classified ad for a 51 GMC pickup, always wanted a 5 window swb, this ad didn't say, but it does say nearly rust free, turns over doesnt run, and $1500, so IMO, this is pretty well a guaranteed good buy even if I have to convert it to my desired truck. My questions are, what are the major areas of concern with these trucks, rust, frame issues, etc, and is it madatory to do an s10 swap to may them driveable? thanks for any help