The COAE-A heads will match closely to the C1TE heads both in valve and combustion chamber sizes. Over the years, I’ve pulled several Y’s apart that had mismatched heads both in valve sizes and combustion chamber sizes and they ran okay and without issue that way. But in an ideal world, you would like to have heads that match in both valve and combustion chamber sizes. For all intent and purposes, all 1960 and newer production heads should be interchangeable.