BPE HEI Distributor

I have a 408 with a 750/3310 carb, HEI style distributor, 727 with 3500 stall converter, 28" tires with 3.23 gearing. Am using MVA as the engine seems to like it. Though I can feel slight vacuum at idle, there is such low vacuum at idle that the vacuum canister does not respond (vacuum gauge at idle jumps all around so useless to tune with). The off-idle transition does not bog, but I think it should be a bit crisper. I tried running without VA but had to advance the timing such that the starter dragged when the engine was hot. The idle screws are both out about 2.5 turns. The engine will not run with them any further in. I changed the PV to a 3.5 and that helped the low speed pep & the plugs no longer run pig rich. At idle/low speed the exhaust smells rich. I've never "tuned" an HEI distributor so wondering if anyone with a BPE setup has done so. Distributor cent. advance is below:

Initial timing=16 @ 650
16 @ 1000
26 @ 1500
31 @ 2000
34 @ 2500
36 @ 3000