How much vacuum?

[1972Blaze]

I am getting almost no vacuum at idle where my vacuum advance connects to the carb. I am getting what seems like strong vacuum for the PCV valve and power brake booster. I am getting vacuum at the manifold fitting for the A/C, etc. The truck is a 1972 w 350, auto and original 4 bbl carb, recently rebuilt by a very reputable source. I have not detected any leaks in the vacuum system.

How much vacuum, if any, should I get at idle on the carb for the VAC? How much at the manifold?

If the lack of vacuum is not normal, what are the most likely culprits?

Thanks.