Dude you are confusing the effing heck out of me.
I don't think a vacuum resistor has anything to do with anything on these motors, as I sure as heck don't have one.
You have a fuel pump that don't know the output of....the 80-90psi pump will be regulated back properly, I would be concerned that a 65psi (peak) pump might run the risk of being insufficient under certain load conditions.
That FPR listed doesn't fit LS series truck according to the "make it fit" listing on the autozone website....how did you end up with this one? Did the original one fail, or are you for some reason (please tell me no), running 2 fpr's?