If the heads used on the crate motors were similar to the ones you could buy over the counter, without some reworking, I don't see how they could have been making 575hp out of that combo.
Would have been "fun" to test one right ootb......eer.....oot-crate.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads