I still have a set of bare castings. The Mustang runs iron with port tongues and a Funnelweb 4V. Easy 500HP. To get the old iron heads prepped here - cut for studs, bronze thick wall guides, seats cut, spring seats cut, etc it's close to $1200 for the machining and labor. That's with no parts. With AFDs close to $1500 bare, why bother.
