I believe '84-up fit no probs on the older '73-83 trucks. As far as the hookup to hydro booster, I don't think there were differences in the pedals, but I could be wrong. I think the pin on pedal is larger for the hydroboost, the pin where the rod hooks to? Not sure. I fitted a '97 hydroboost unit to my '73 (stock '73 pedals), I machined my own booster rod. Basically just the eye from my pedal end, and the hookup from the booster end.
If possible I would try to find the pedals from an '84-up that had hydroboost, but I think that setup was pretty rare, only some 1 tons had hydroboost, all diesels did too, but consumers diesels were only available with automatics. YOu might check medium duty chasiss from that era as well, the cab is the same as out trucks, might have same pedals, and lot more likly to be manual trans.