Yeah all the other cheap pumps state 7-8 psi or no rating at all so its likely a waste of time. I don't know if the old pumps put out less pressure or perhaps the carbs were more tolerant.
the newer pumps are just crap... i am kicking myself for throwing away my 62 pump.. didn't know there were rebuild kits and didn't know how bad new pumps are.. even the $200 edelbrock pumps have issues