Help identify aluminum heads

427shark said
Just got off with mahle, which BTW has one of the best customer service support departments I've ever dealt with. If the heads are the speed masters 78cc the CR is approx. 11.8 to 1. We know the piston & the rod is a 7.1, I do t have any info on the crank though. Assuming it's a 4.375 the engine would be 520ci

You are assuming flat tops? I think I would get a cheap inspection camera that plugs into a phone, and look through a plug hole. 11.8 with a 220-something at .050 will be a full-on race gas only engine. (If it IS that high, the first thing I would do is convert to E85 if it's available where you are. )