Need Quick Fuel carb tuning assistance

Combo is 67 dart
340 ci
Dynoed 400hp
Timing is 20* at idle
34* total
4 speed manual trans
3.55 gear
I had a different carb a year or so ago (AED) and it didn't have quite the easy tunability as the one I have now. I never bothered much with the other carb, just got it to cruise and idle ok and left it alone. I now have a Quickfuel SS 650 DP, with all the adjustability you could want, need to start tuning. I know way more now than I did then, so things are getting easier. I have the quickfuel to where it will idle in the low 13's and cruise there as well, but the closer I get to 2700ish rpm it will start to drop on the AFR to high 12's or 13", so I know there is tuning to be done in the main circuit.
Now here is my main concern. Just say I am crusing along and have to slow down enough that I can shift into first gear (no traffic, 4 speed manual) and floor the throttle, sometimes it will gas foul a plug. Just did it an hour ago. Ran like crap on the way home, pulled up in the driveway, shut it off. 1 minute later opened the hood, started it and let it idle while checking timing and it clears up and starts idling well again. I know I can rejet the carb and restrictors, but should a BOX STOCK Quickfuel SS 650 DP do this on my combo. The Holley 4777-4 I had on it originally was awesome. Never had this issue.
My first question is, should this carb throw that much fuel to this motor to foul plugs. Engine is low milage and in great condition. I have 245/60 cooper cobras on the rear and in 1st gear can light them up at 25 mph.

Quick Fuel SS-650 SS-Series Carburetor 650CFM

Booster Down Leg
Brand Quick Fuel
CFM 650
Choke Electric
Circuit 2
Fuel Gasoline
Fuel System Carbureted
High Speed Air Bleed 31
Idle Air Bleed Size 71
Material Aluminum
Model Super Street Series
Primary Main Jet 70
Primary Power Valve 65
Primary Pump Nozzle Size 31
Product Type Carburetor
Secondaries Mechanical
Secondary Main Jet 76
Supercharged Application No
Throttle Bore 1-11/16 inch