Yeah,
I see em over at the track (One Mustang used them at the World Ford Challenge) now and again. But you have to need to move some serious air to make use of them. On the other hand, they look very cool under your hood, and they aught to!
I could see a Dart block, with Windsor journals, and a 4.100 stroke out to 450 something cubes and those heads with a .600 lift cam. Man THAT would make a motor! You'd have 20 large in it, but what the heck!....
Eric