To much cam??

I'm having an issue and would like to get some other ideas. We built a 71 383/727 to install into a 72 Swinger with PS and PB. The engine is bored .030, 9.5 flat top pistons (cast), stock 906 heads (new valves, seats, 3 angle valve job) no port work. Edelbrock dual plane intake w/ 750 carb. The cam is a Comp 284H (484 lift, 104.0 intake centerline, duration @.050 lift 239int, 246 exh, lobe seperation 108.0). 2400 stall conv. and Schumaker headers with dual exhaust. The cam and crank gear marks were aligned when installed and the balancer is 1-2 degrees from being dead nuts on.

The issue is the engine only develops 5-6 in. vacuum at idle (15 deg.initial timing) and 10-12 in. at 3500 (34 1/2 deg. total timing). If I give it more initial timing the vacuum will increase but I end up around 50 deg. total timing. The PB hardly work, it wants to die when put into gear (unless I turn the idle speed up).

I wanted something that had a lopey idle but I need the PB to work. The combo works great above 2500 rpm but I need something a little more streetable. Is the cam to much??? Any ideas, thoughts, comments, suggestions would be great.