That's basically it, Urban. They're good for stockers, but not amazing. With some work, you can make them flow very well, but by that point you're better off buying a set of aftermarket heads. But if you can get them cheap and ready to bolt on, they're not a bad deal. Almost anything is better than stock pre-E7 heads. The exhaust port castings are absolutely terrible.

 

the only 351w heads they are comparable to are the C9 - D0 castings. all the later model 351w heads were the same as 302 heads with larger head bolt holes.

but yes, on a 289/302 the early 351w heads / gt40 heads are a great low budget addition.