Dick, I have a mech in my car, and use the super precise one when needed to adjust the regulator. It lives in my toolbox, and was semi pricey. You're welcome to borrow it anytime. I can ship it to you in a day if you like.
My in car guage has proved useful in troubleshooting, so that I know if, when I have issues like yours, that it is a case of lack of fule getting to the carrb (out of, errr...gas, clogged fuel filter, fuel pump issues, etc) or it is in the carb itself. Saves time at the track.
(Actually, my new 7s Only carb needed adjustment at MO, and I jumped right on float level fine tuning based on my on track observation of proper and steady fuel pressure.)