Gt40 Heads Worth The Work?

They are worth a try IMO. I have a set as well. We were going to swap them onto my wife's 84 convertible that we also swapped a Lincoln Mark VII 5.0 into, mass air converted, installed an Explorer intake and headers. We never did get around to it, but we still have the heads with new springs installed. We plan on swapping them into her "new" 87 GT convertible when we get the opportunity. From what I've researched, they're good for a small boost without porting. You're not going to break any land speed records without changing everything, but I imagine you would notice a difference. Better breathing heads are always a pretty good investment....

Even 300 I think is a bit high for those.

I've seen the GT40's for sale locally for $150-200. GT40P's have gotten so common I'm using a set as a doorstop. I couldn't sell them for $100 when I tried