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.