I am running a 2056 using Ljet fuel injection. The original fuel pressure regulator I had only maintained 28 psi. Ljet fuel pressure is supposed to be at 35 psi. I installed an adjustable regulator and adjusted the fuel pressure to 35 psi. Will the additional 7psi change that air fuel ratio?

Yes, a little bit.

The L-jet I'm used to is the Nissan variety and they had a vacuum referenced fuel regulator that would only run full pressure (also 36psi) with the vacuum line pulled and plugged.
At idle they would run 7-10 psi LOWER pressure with the vacuum line connected.
You could blip the throttle and see the pressure jump up.

At WOT there is almost no vacuum in the intake and fuel pressure would be maxed out at 36psi.

If I saw one of these systems at 28psi (no vacuum) I'd be worried about the fuel pump, restrictions, etc...

If you changed to a static regulator that does not use a vacuum reference AND the original system used a vacuum referenced regulator the fuel maps will work fine at 36psi at full throttle ONLY and car will idle best at 28 psi.

L-Jet HAS to have a vacuum referenced regulator in my book.

The fuel pressure regulator on my 75 914 looks like it would work fine on my 75 280z.

Same puppy...

Thanks for the info.