273 302 318 340 build

The E-4 won't overcam the 273 with 2 barrel pistons. I've built plenty of them. 273's don't have the compression problem that later engines have. As 318willrun said, he has given you a blueprint for a 318. It is all about air flow, matching components, and tuning your combination. And getting it to run where the car lives, or how you drive it. Don't get hung up on compression, and getting every .001 of an inch. Things are not that critical on the street. If you are racing in class, that's different.