If oil is coming out of the pressure port in the main gallery the pump is working. Plumb a gauge to that port and be sure you're spinning the pump clockwise from the distributor hole. If you use a digital watch or a cell phone to tell time, get an oldtimer to explain what "clockwise" means. If the engine has an oil filter, it might take a couple of minutes of pumping to get the system to come up to full pressure.
Getting more than a slow seep from the rocker arm weep holes could also take a while. The volume of oil going to the rocker shaft can be very low on some engines, as the oil passages can have restrictors to limit volume to the top end. That's a feature, not a bug, as stovebolts are engineered to sacrifice the rockers if necessary to save the bottom end in case of a low oil pressure situation. On 216s and spray-oiler 235s, the rockers get no oil at all until pressure at the main bearings exceeds 15 PSI.
Even with a brand new pump (and definitely a used one) I always remove the base plate and pack the gear chamber with vaseline. That assures that the pump will self-prime quickly, and the vaseline dissolves as soon as the oil gets to it. DO NOT use wheel bearing grease!
Jerry
