ditto what teddy said.
oil spring is fine if it makes 50 at startup.
was the oil pump rebuilt during this rebuild?
cam inserts can be made if needed.
me personally? i like 15w40 oil.
as a rule of thumb, if it will make 6psi per 1000 rpm at hot 'idle' it won't self destruct. obviously more is better.
hapve you ever repalced the gauge to see if that is what you are really getting. a gauge that is 3 psi wrong means alot when you are looking at 5 psi or 8 psi :)