Usually I just fit a lenght of hose around the mech pump and leave it in place but thats because I'm fitting them in the field. In workshop I just cut a 5mm ally plate to size drill 2 holes add sealant and gasket then bolt it up. If you want to mount the pump to that bit of ally, make it out of 10mm and drill and tap to suit the bolt of choice BUT dont drill all the way through or if you do, usel loctite 567/577 to seal the thread.
Oddly, I've never had an issue with these pumps priming any landrover I've fitted them to so long as they are fitted post sedimentor (sometimes filter) AND all the seals are good and tight.
ANy one of the pumps you've put up will do the job, I've got a couple I got from garage sales at something like $2 each that still shift fuel more than well enough for a worked up tdi300

