will this run on pump gas ?
Adam, Brian offers those heads with chambers from 62-67cc...
http://www.immengines.com/rhsheads.html
I would not base anything on the advertisement from hughes unless they actually cc the head, put a decent depth surface cut on them or have the valves very proud in the chamber.
I think you can get acceptable CR's with 107's, RHS heads and quench . Verify chamber volume you ate going to receive.