If you decide to go this route, a gauge out of a non-turbo charged airplane give best resolution:
Edit: One thing to remember, the manifold pressure gauge needles move opposite those on a manifold vacuum gauge. Opening the throttle on the manifold pressure gauge moves the needles higher vs with the typical carb sync vacuum gauge set-up the needles will be higher at idle speeds. This could cause confusion when adjusting the carbs.
I’ve been balancing carbs with a manometer since the mid ‘70’s starting wth a Kawasaki Z-1. Worked great on my 912ULS. Search for “ carb stick manometer”. NO question about having matching gauges and no valves to fiddle with.
Regards,
After years of working on motorcycle. I have never come across anything that works better than Morgan Carbtune, around $100 for two carb. Made by knomes
in England.