I built a 500hp 395ci Poly pump gas engine with Bruce Toth ported heads that flowed 247 on the intake and 166 on the exhaust at .600 lift I have it in a 66 Plymouth Valiant Gasser that runs low to mid 11 second 1/4 mile passes thru the mufflers with street tires. Here is a link to a video where you can see how a poly on pump gas can run with some work car can be seen at 1:32 into video: