Suzuki 2 Strokes

I recently cracked a head on my T500 at a land speed event. It was the 4th pass, 1.5 mile track. It cracked near the end of the last pass. Anyway, something I just noticed is that the liner protrudes from the cylinder casting about .002". I'd never noticed this before. A spare set of cylinders is the same. I don't think I've ever seen this before. Is it normal to have this step?

I was running a .010" copper head gasket. Would the OEM aluminum gasket (thicker) work better? Are these heads normally in flexure when being clamped? It doesn't seem right but my spare cylinders are the same.

Comments, thoughts, etc. appreciated!

thanks,
Frank