I have a 340 Duster running a Holey 750 double pumper primary jets 72, secondary jets 76 power valve 45 Edlebrock LD340 intke. Your jets are too small so you have to push the throttle so far that you are always into the power valve. What is your elevation? I'm in southern California pretty close to sea level. Your cam sounds like it is a little too hot for the street (Sig Erson hyFlow 2?) The Sig hyflow 1 is a better choice. My Duster gets 12mpg with 3.55 gears with posi and the stock cam (hydraulic). I have a 4 speed. It turns low 12's/high 11's depending on the track.
If you have an automatic, what is the stall speed on the converter? My V-8 Vega has a 700R4 2200 rpm stall, 3.08 gears with posi and Sig Erson HyFlow1 cam with Fuel Injection. Both cars have headers. You can write to me for more details at barry91765 at g male