What's a safe fuel pressure?

Last year I ran my 85-z on a "babyshot" (50 hp) of nitrous with no problems. The Edelbrock wet plate kit was working awesome. Towards the end of summer it started getting a rattling sound from the solenoids. I knew it was from the FPSS because it did the same thing when I was setting it up. This year I got out my car and realized that I had a fuel "problem". I tried adjusting my FPSS down to a suitable level, but it seems really low.
What is a safe fuel pressure to run my nitrous system at? I've got a stock mechanical fuel pump that was new early last year. Is it dying out? or just not keeping up with the fuel consumption when I'm spraying? I DID have my FPSS set to around 8psi but now it seems like while I'm spraying it will fade all the way down to like 5 or 6 psi (I bypassed the fpss to doublecheck that it was the problem). I like to think I had learned my limits with the 50 and was thinking about kicking it up to the 75 or 100 jets, but if this is a problem with the 50's I'd hate to blow up my motor increasing the nitrous to a bigger shot. Any suggestions?

A stock, engine mounted mechanical fuel pump? Feeding both the engine and nitrous solenoid? The nitrous kit is designed to operate at a specific pressure. It's probably 6 psi but don't quote me...you'll need the correct jetting and pressure numbers.

My stock EFI pump had a hard time keeping up with my 305 carb and nitrous setup. Both ran at 7-8 psi off of one regulator and they kit would delay a good 2-3 seconds when activated because the FPSS was set at 6psi and my pressure would dip down to 4 psi when the kit was activated...it would climb back up to 7-8 and the nitrous would kit. More fuel pump and seperate regulators is the solution for this. Keep the carb happy at a set PSI with one regulator and tune the nitrous system with a seperate regulator. Goodluck!

Yes, and I read my nitrous manual (imagine that, it had some useful info I forgot about) and it said fuel pressure should be at 5.5 psi.
Thanks for the reply AutoRoc. Do you have any suggestions on regulators?