If you're planning on reselling said truck, pull the 307 and dunk in a 350, your resale will go up. Most buyers will try to talk you down due to the supposed bad 307 (which since you would be changing the cam and timing set, would be perfectly fine. If you DO opt for the 350, keep the 307 for another hot rod project and tell everyone its a 283, which all the retro guys love.
If you build the 307, DV's advice is spot on. Realistically you could put 3.73s in the back of your truck, and a 700r4 or 200-4r overdrive automatic (or a T5 or 833-OD stickshift) and have an absolute riot for a street truck