I have my "spare" fuel pump stored with a couple of studs, made from threaded rod. If I ever need to install this unit in the field I can insert the studs, slip the pump over them, and tighten down the nuts. Once it's snug against the block I can always remove one nut and stud at a time and reinsert the proper bolts. That's my theoretical plan anyway. I haven't needed to put it to a test yet.
This idea came to me as I was replacing the pump in a parking lot several years ago. I struggled to get the bolts started, especially the second bolt, as I had limited reach with both arms together. I eventually got it, but I kept thinking that if I had long enough bolts, or studs, it would have been much easier.