Kenparker: oh, the younger generation that can't drive a stick shift. What a shame. :-) An auto trans takes all the fun out of driving an old truck.
09JK: Your plan is sound. Your priorities (in order) should be stop, steer and go. Get the brakes and steering squared away before putting much time and effort into the engine. As far as an engine swap goes, you need to do some soul searching with your son and define what your needs really are. Newer and bigger is not necessarily better. Unless you want to race your buddies or smoke the tires on a regular basis, there is nothing wrong/deficient about running an in-line 6. I have a 58 Suburban that a previous owner swapped in a late 70's 250. It has plenty of get up to enjoy driving. I haven't tried towing with it yet, so that may be an issue in the future. If more power is needed I'll look for a good running 292 to put in. I'm kind of nostalgic for the old straight 6 engines. I would caution you on installing a GMC 302. I don't have any personal experience, but have been told that the block is longer and isn't a simple swap out. For details on that issue, look in the engine or HiPo forums.
On the floor pan issue; if you can get a good deal from a buddy, I'd go that way. There is a good amount of room under classic trucks, so I wouldn't be overly concerned about putting in an extra large trans tunnel. The only thing I'd suggest would be to make sure the guy uses adequate bracing in the cab. Depending on how much of the floor gets removed at a time, there is a potential for the cab to get out of square. The floor provides a lot of structural stability/integrity for the cab. Some temporary cross bracing in the bottom half of the cab might be a good idea. For further guidance, check out the paint/body forum.
Anyway, congratulations on the acquisition. It is always exciting to get a new generation interested in old trucks.
