Hardened valve seats - do they really matter?

And for whoever said what the CR would be on a /6 with that much head shave it won't be that much. I haven't seen one that is as high as 8:1 to start out with, even though they "advertised" 8.4:1. They're actually in the 7s.
And with it being doubtful to find an original shim steel head gasket chances are better than even that the replacement HG will be thicker than that original one which reduces CR further from stock. You basically gotta cut the head 0.020-0.030 just to make up for the thicker replacement HG