I bought an L76 to build for my camaro, and the builder is telling me the motor came with 243 heads compression is at 11.5 to 1 . Supposedly this motor came out of a tahoe that was warrantied. The highest compression I can find listed anywhere is 10.4 in a G8 gt, but that has different heads than what came in this Tahoe. The rotating assembly had material removed like it was internally balanced. Is this some kind of a screw up from the factory?? Trying to figure out where compression will be with L92's.