IIRC
The formula is ; 1/2 pound of fuel per horsepower per hour, plus reserve.
A mild 360 at 250hp would need 125pounds per hp/hr or at a fuel spec of 6pounds per gallon, I get 21 gph. This would be the maximum requirement.
The carb don't care about psi so long as it doesn't blow the float valve off at idle. And so long as 21gph gets delivered to the fuel bowl at max power. If your float valves have tiny holes, they could become the choke point, giving you a high psi, but a low gph; giving you a false security; not good.
At 300hp the result is (300x.5)/6=25gph
Hey, since we know this now, what about fuel economy?
Well if it takes 40 hp to propel your car at 60 mph; then (40x.5)/6=3.33 gph .....and at 60 mph you are traveling 60 miles in one hour... so that would be 60 miles using 3.33 gallons .... which translates to.....18 mpg.
jus saying
What about running down the track?
Well say you were able to generate the 250 hp for the entire distance and did it in 15 seconds;
(250x.5)6 =21 gallons per hour or 21/60 =.35 gallon per minute.... or .087 gallon required for the run, which is 2.85 ounces. What's that in ccs? IDK,325 maybe?