Here's a better look at the dizzy install. I'd prefer it if I could put it in one tooth ahead of where it is, but the base of it then hits the first bolt that holds the lifter cover in place.
IMO it's false economy to put a used oil pump in a fresh engine. So I ordered a new one (Melling M-67A) for a '64. It takes a 5/16" drive shaft rather than a 1/4". So I didn't have to thin down the stock one, just cut about an inch off the new one.