Tuning a Proform/Holley carb, what parts and tools?

I'm guessing that the regulator can't bleed off extra pressure. That would make it hard to judge the adjustment in one direction, probably in reducing the pressure. See if the directions have anything about this. Also, depending on how its designed the pressure regulation may be plus or minus some amount. Lets say baseline went from 5.5 to 6 andlet say the plus minus is 1 psi. 5.5 + 1 = 6.5 which is just OK and may have been only an occassional problem, but set at 6 it easily goes to 7 psi.

As far as the gage, this is first I've heard of one being temperature dependent. How quickly they react (damping) is a more typical concern. Most are just a closed tube and some fine springs and movements. Somewhat fragile yes. When they fail, its usually consistant (doesn't return to zero or whatever) so I'm not help on this one. I can't even think of a reason why a mechanical gage would be so temperature dependent to be off by 25%