oops...i re-read your post, you are hooking it up to a 2bbl carb....i believe that is what determines the difference in the fuel pump, the 4bbl pump has a return line, and the 2-bbl dosen't. In that case, just plug the smaller return line....OR
Put your 4bbl intanke and carb on the 307 and run the 350 fuel pump. Gotta have a 4bbl
