I put a set of 2002 GMC seats in my 1963 C-10 recently, and would just like to take the time to say, they WILL fit easily into any 1960-current GM truck. The only thing you may have to do is drill new holes in the floorboards and install new bolts. These are VERY comfortable seats, and have the added bonus of integrated seatbelts.
Since you are a machinist, you should have no problem at all with this swap. Good luck!