Very Low Vacuum

Recently got my 360 running in my Duster. Cant drive it, LOTS more work to get there. lol

Anyhow, it's 11.2:1, MP 292 508 cam, 2.02 intakes, 915 heads are ported, Torker II intake and 750 vac Holley.

It's idling at 900 rpm @ 3" of vacuum. I have this PCV, M/E Wagner Performance Products – High Performance Crankcase Ventilation Systems it's not set up yet, but I've plugged it, with no difference.

It hasn't run in 10 years, and I know I played with idle feed hole size, but don't remember what I did. I also drilled holes in the primary plates. (Maybe 1/8"?) Today, I plugged the holes and cracked the secondaries. Still @ 900 rpm w/ 3", but it doesn't "run away" so much.(It was hard to get it to return to idle before I did that.)

I cover the airhorn w/ a rag slowly and it doesn't pick up, like a vacuum leak. I sprayed around the carb base and manifold, no rpm increase.
Big cam equals no/low vacuum
You can adjust the carb and timing all you want, you may get it to come up a couple of inches but you will never see vacuum like a stock engine creates.
How much vacuum do you need? And what are you going to do with it?