My 63 has one talk about torque same as yours 305 v6 E I'm in the process of restoreing it now talk about a good looking unique engine when there all cleanded up an painted....check the plate on the kicker panel some of them came factory or dealer with more h.p. and it should tell you what motor it came with but you'll have to check the cab to engine #s to know for sure those are the sought after ones in my opinion there's a couple guys here that have rebuilt them from top to bottom there's. A couple places that offer almost any stock replacement part or hop up part you could ever want !ill get you a list of the sites and and pics of mine o yea rj might have some of the hard to find compents an extras like p.s. ac ect.you'll have to ask.
A nut among the bolters sure ill like it quite well here.I enjoy the 60-66 "iron" I like the gmcs,chimys,chevys regardless these trucks rule! Mine 63 gmc fleetside long bed. Custom cab 3/4tfirst truck<being restored

62 chevy short bed fleetside 1/2t