Hughes must have gotten the “really good” ones from Edelbrock.

The ones I’ve tested were more like 409@.800, on a 4.500 bore.
Exhaust was 240 without a tube and 273 with a 2-1/8” tube.

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads