budget 273 build

The absence of piston choice unless custom made seems to be the occurrence. I have no problem with running a little higher than 10.5 to 1. I think If I run 91 octane pump gas through detonation shouldn't be an issue, the ignition timing may be more retarded than compared to the lower compression. Also a longer intake duration could be used to bleed of cylinder pressure and change the dynamic compression or a stock cam grind could have the timing retarded. But I think I'll be fine with the 91 octane