Power valve doesn't do crap at cruise speed.

Sounds like a comp XE274H camshaft. The vacuum you have at idle is pathetically low for that camshaft. It should be pulling at least 11" and more likely 12-13 at idle of about 850 rpm.

My favorite question for this stuff. What's the initial timing on the engine?

Please don't say it's total timed at x,xxx rpm... cause that doesn't mean squat. Put a light on it at idle and see what you have. If it's less than about 15* BTDC, it needs to be around 15-20. You'll have to open up the distributor to limit mechanical advance to hit your total number in most cases.