I think if you took them to a shop to measure the Edelbrock RPM valve spring pressures, they would be around 120 seat (1.88). I can't guess at the spring rate and open pressure.

But like I said, many reported differences over the years. The danger with too little spring pressure is valve float and the resulting valve train damage. It could be mild, or could ruin the valve seat sealing, bend pushrods, break rockers, not to mention weaken the springs. If a retainer or locks(keepers) let go, it could swallow a valve. I would be careful.