It is the mighty demon 650 double pumper(mechanical secondary), I paid $600 for it new with the fuel line. Used for five months and jetting was changed up two sizes on the front, but can put what ever you want in it, if interested. Asking $450, still works like new. Barry Grant 5282010GC is the part number if you want to look up the specs.
also have a holley 735 C9AF-9510-M with authentic autolite tag and a holley 600. Open to offers on them.