Been dealing with this issue since the mid 70s. I have always kept 2 items laying around at all times that I had pulled from junk yards. Ballast resisters and fuel pump push rods. I bet I have changed a couple of dozen over the years in big blocks. I got a heck of a deal one time on a numbers matching '71 GTX due to a worn pump push rod. Never had a problem just throwing another one in there.