Originally Posted by F-BIRD'88
If you are going to spend the money to get another set of heads get a head that flows the numbers you want. You can mill a S/R head down to the intake valve seat edge and or the spark plug hole boss. Which ever comes first. That is the physical flat mill limit. Should be able to get to 69cc with that.
"and have them ported" Porting S/R cast iron heads is time consuming and labour cost prohibitive.
These heads, like most stock heads are not worth paying someone else to port them. Its a do it your self thing or else its just not cost effective.
Unless you do the porting yourself and pay some one just whats required to finish them up with required machine work, its cheaper and more cost effective to just buy a aftermarket head that flows the numbers you want.
Point well taken
I probebly could mill them, more than what they are, but i plan to leave it alone for now. Maybe in the not so distent future, i'll be able to land a set of alluminum heads and i'll go from there.