I have a 10 to 1 318 with a factory 273 2bbl cam and it has a 195 t-stat 2.76 gears LU trans and it does not ping on 89 octane even under a load going up big mountain passes and a 6x12 enclosed trailer. With slightly bigger cam, 180 t-stat and better chambers than even my heads (302s) have he will be fine. I have a thermo quad carb set very lean and uncoated headers putting off a lot of under hood heat too boot and have knocked down a best of 29 mpg with this car. Higher compression equals higher engine efficency from thermal expansion rates being higher and higher compression gets more exhaust out to make a less diluted intake charge and by squeezing the mix tighter it burns faster (DUH) and will do more work on the piston instead of continueing to burn as it goes out the ex valve. This is the reasoning that you need to get through your thick skull. You will get higher miledge from higher compression assumeing you don't get the dome in the way of a fast complete burn, that is why flat top pistons are better than dishes or domes. And that is how higher efficency of the higher compression makes up the 20 cents differance in a gallon.