Boy, does my son's slant run crappy!

Man, what a difference it makes when all cylinders are firing and the carburetor is working as it should!

Fixed a plug wire, installed a rebuilt (not reman) carb, did a little quick tuning, and the test drive went great. I still want to set the valve lash, check the timing, replace the rubber fuel lines, tweak the idle settings, and replace the air filter.

What should I expect the vacuum reading to be? Right now, it stays at a steady 15 in. at 750 rpm idle.