If you want a cheap head you can fix up by by home porting them and
installing decent vavles etc.
And open up the chambers too.
Look at a set of the new version 210cc Pro comp heads.
as sold by Jegs etc.
Buy a BARE SET not assembled.
The chamber is listed at 64cc but probabily bigger 67ish and you can make it much bigere,,, by hand.
Others like DR J's performance actually make a fair good cylinder head out of these
starting with a BARE casting.
You can too.
Normally I don;t recomend these china heads but........ They are light years ahead of the crap you got now and can turn out very welll with some smarts and elbow grease.
They need full home porting, full inspection and most likely a valve job.
Buy new manley street valves,,,springs etc.
The price is right.
Aluminum is much easier and faster to port and carve the chamber.
now you can make horsepower.