Head gasket getting oval?

Question: How do you know for sure that youhave 10.5:1 CR? SInce it is a bought engine, unless the combustion chamber has been measured or the piston/head combo is fully know, you could be off .5 point of CR pretty easily.

The bolt length does need to be checked, but it seems unlikely that it would be so consistent across all of the holes; I would think it would bottom out on a hole here and there, not on them all. Similarly for the detonation; I would not expect it to occur so evenly; one or two cylinders would show it much worse than the others due to mixture and other variations, etc.. This makes me think that the intake alignment (head lift), surface finish, torque issues, or gaskets are the likely causes.