The best way to eliminate your mechanical pump is to block it off with a chevy big block fuel pump block off plate, or make your own. I think summit has them for about $10. I do not recommend a mechanical pump to anyone. I've used one for a long time because I used to run WVO, and electric pumps capable of reliably pumping WVO are very spendy, like $400. I have had multiple mechanical pumps on it, airtex, delphi (which are actually airtex pumps in a delphi box) and carter, and they are all pathetic. Only one I haven't tried is one from the ford dealer because they're like $130. I used to think the mechanical pumps are ok, until they all started failing on me, and until I moved to a colder climate. After installing a fuel pressure gauge, I have noticed that below about 10 degrees, they do not produce pressure. They'll maybe do 1-2 psi at idle, but with any throttle will drop to zero (and you would never know it without a gauge - the engine runs fine). This is with pump diesel, that I blend with PowerService myself. My best guess is that the rubber internals can't do its work when its cold and stiff. Add being a pain to change, hard to prime after a fuel filter change, the possibility of filling your crankcase with diesel and its hard not to just go electric.