My truck had a C10 4th generation (1988–1998)
60/40 split bench seat when I bought it (like the '96 seat you had) and my truck had the stock in cab tank.
I have since relocated the tank to the frame and installed bucket seats.What I learned: The reality is that removing the in-cab tank does not help leg room. The top of the seat hits the back of the cab before, or at the same time, as it hits the gas tank. The designers at GM based the tank design so it wouldn't limit leg room.
One thing that will help you with space between the seat and steering wheel is an aftermarket wheel with less dish. I did this, see post #26 here:
Grant #992 steering wheelIf you are wanting a bench seat, and since you stated "
I intend to keep the truck mostly stock" rebuilding the stock seat is probably your best bet, IMHO. I have yet to see any seat that looks "correct" in a nearly stock truck other than the original.
Hope this helps and good luck to Ya!

John