A little clarification on adjusting idle air mixture on eddy carb

I had a vacuum gauge from work on it but it was one of the cheap ones, seems like it was aaround 13 in/hg at the best i could get. May be time to invest in a quality gauge? Ive also heard the bigger the dial the more accurate it is. Are there digital ones available? Are they any good. I know ideal af is 14.7 in/hg. Doesnt seem like im far off but some of that could be the cam

Stubbled on this article
Air-Fuel Ratio Meter Tuning- Car Craft Magazine

So about 13 in/hg is ideal?

Also not sure if it was my gauge but it didnt seem like it varried to much when turning the idle mixture screws. Ended up setting them up by listening to the rpms