VACUUM too low

[IMPALAMAN1]

Hey fellas,
i got my 68 back on the road and the timing (billet msd with vac advance plugged, 6a box, blaster 2 coil) is now set right..... the carb (demon 625? vac secondaries, elec choke not hooked up) with the carb tuned it seems that i have no more vacuum. it is at 5". the motor is a 327 with the 202 heads z28 springs stamped steel roller rockers. intake is the airflow research. cam is the comp cams energy extreme the one just below the 168 with the keith black flat top pistons... 9.5:1. factory crank and connecting rods.

the car has power 4 wheel disc brakes and this is where my problem lies..... 5" of vac doesnt lend it much pedal help.

the car idles at 500 rpm... which seems real low to me.

i do have 2 extra vac tanks.... 1 for the brakes and 1 for the headlights.