73-87 Pickup wheels, at least the 1/2 ton 2WD, are regular old GM 5x5" pattern, you can probably poke around and find one that already exists.
1/2 ton 3/4 ton 1 ton? 2 or 4wd? or simply what bolt pattern are you talking about? are you looking for a steel wheel or alloy or (gulp) billet? these are questions you need to answer before anyone could tell you anything
Base model 1/2 ton wheels were 15x6. They are pretty easy pickins since most folks go wider wheels. I just powdercoated this pair awhile back. They came off an 80 model truck and are 15x6.