Hey guys, got a question.

I have been trying to narrow down a loss of power (I think). The car has a Demonsizzler Thermoquad carb now that is way, way off. It doesn't seem to matter what I do, the a/f for most the run is in the 9's and low 10's. After a couple passes the plugs are black. The exhaust manifolds are changing all sorts of colors due to what I believe is raw fuel burning in them. I have smaller than factory 340 jetting in it, and have tried messing with the air door. I have tried different fuel pressures with no change.

I have a holley hp series 770 or 780 I believe that I am going to throw on and make a couple passes with. I would like to have it semi close with maybe a lean side jetting to start.
The motor is 402 cu in, factory manifolds, and intake, solid roller.
The motor went 11.57 @ 117.9 in a 3670 AAR with a six-pack.
Now is in a 71 Duster, 3166 w/ factory intake hogged out and has gone 11.95 @ 113

What jetting is good to start?

Thanks