JohnRR, unfortunately I don't know how much milling has been done.

Mopartforlife, that's what I always thought about hydraulics, that they "took up the slack" unless a huge amount of milling was done. The car starts/idles great, and runs smoothly at any constant rpm. The only performance problem is a major hestitaion at all rpms when accelerating, which may be due to other factors I suppose. Right now I am just trying to figure out the low vacuum.

I have heard there is a device made by Snap-On that is essentially a smoke generator. This device seals over the top of the carb and blows smoke into the engine. I assume you have to plug off all the vacuum ports, etc. Any leak produces a puff of whie smoke. My engine building friend used this device and found a grain-of-sand size hole casting defect in the body of one of the carbs on a six-pack set-up that nobody could get to run right. We're going to try it on this problem.