Background: I have a freshly rebuilt SBC 350 with 76cc (1.94-1.5) heads a Weiand dual plane intake Holley 600 cfm with vacuum secondaries and a mild flat tappet hydraulic cam: 224 @.050 duration with .465 lift, the LSA is 112 degrees. I have the initial timing set at 14 BTDC.  

Problem: I only get 14 hg of manifold vacuum at idle (800 rpm), further it won't idle smooth without the HEI vacuum advance being connected to full manifold vacuum port, lastly the idle mixture screws are out 2 1/4 turns.

Things I've done: Had the carb checked on a mule motor, pressure checked the manifold for vacuum leaks and have adjusted the valves (1.52 comp cams roller tip rockers)using both the "spin the push rod" and "jiggle the push rod" techniques...
any ideas  

additionally. all other vacuum readings are normal, to include at 2000 rpm the vacuum is 20hg and at 3000 rpm 21hg; also, I can't drive the car as I'm in the middle of a frame off and the body isn't on the frame...