Fuel pressure too low?

[OneLethal87GN]

My K-B hood-mounted gauge is reading around the high 20s at idle with the vacuum line on. Is this too low? I read that lower pressure makes the fuel pump flow more fuel, yet the injectors flow less fuel. My car seems to shut off when first cranked. After 2-3 times of cranking the car will run good. It does this when cold. After warmed up it cranks and runs the first time. Also when cranked cold alot of black smoke will come out. The engine was just rebuilt. It has had the cam broken in, but only has less than 50 miles on it since. Should I adjust the pressure to 43 line off? High 20s seems low to me too yet the car doesn't seem rich either by the scanmaster or the air/fuel gauge I have in the car. Any suggestions?

 

[Rickracer]

Due to the black smoke on startup....

....I would check the regulator, it may be leaking. Pull the vacuum line off with the engine running and see if fuel is leaking into the vacuum hose.