B1 heads were great back in the day but why would anyone buy them today? Koffel hasn't made any changes or improvements to those heads for 20+ years. They never even got around to casting an RB intake manifold. Those heads are frozen in time. If a person is going to build a big engine and shoot for 1000 hp then something like the 572-13 heads would seem like a much better choice. At least you can buy intakes and headers that fit.
