My RHS head were built by Brian at IMM
He did a little porting and his valve job. The flowed 270.
don't see them on his site any more but this look interesting. IMMENGINES.COM
saw those a while back. Almost def they are speedmaster castings. Would like to see the flow numbers with no porting or bowl blend.
Seems to really make his prepped RHS heads seem like a good deal.