73 340 oil pump

Melling is the go-to performance aftermarket brand
no offshore junk- the drives strip out and other bad things happen
that said
pull any new part apart and clean and check, check that the relief piston moves freely
quality new drive with hardened tip is recommended (by me IMHO)
old ones can round off or snap
your clearances have opened up which is why hv was recommended
you may not need it but hard to tell unless you had a mech pressure gauge and saw pressure dropping
all your quality mail order companies have the melling pump