As stated before timing, not to pile on but my Dwayne Porter x heads flow 278-284 which is a pretty much all out effort with an x head. What mufflers? I run a small tire, so this might help. I load the converter until the car starts climb on the suspension. Then leave on whatever light works for you. Then release the brake while holding the throttle steady, the car will begin to roll, just as the nose starts to drop I roll into the throttle. The carb might be small. I have run a 825 mighty demon on my car. Thats 825 crm wet flow. I have run 12.24 with your Stroke/compression and your stated head flow numbers. Solid flat tappet, .555 lift. 1.71 60’
