At Orielly's Auto Parts you can buy early chevy small block 265 and 283 exhaust that have the dump near the back. They are made by Dorman (china) but they are pretty good castings.
I have a set of the Dorman 1963 Corvette fuel injected 2 1/2" dump ram horns. I think they are pretty nice castings. The "china" part of the casting in on the back so it cannot be seen when installed. $69
