"... I wasn't referring to built small valve heads, although that is certain a legit option. I want the high compression small valve heads that are also built..."

I guess I'm confused. Is there a difference in " built small valve heads " and small valve heads that are also built ".

Or is the "high compression" part what you are emphasizing ?

As mentioned, you can not know EXACTLY what your combustion chamber size is, without measuring the chambers. Can't go by online info, or what was advertised years ago. And it don't take a really big cut to reduce the chamber size of a low '70's cc head, down to an upper 60's cc chamber size.

I assume you are saying that you wanna start with some 68cc #46 heads, hopefully with screw-in studs. If so, I wish you luck finding some.