The dulcich test was done in 2001...... which was prior to the revelation that westechs dyno was correcting about 5% high. The stock test showed 357hp....... if you take 5% off it’s 340hp.
Plus, they ran it without a factory air filter...... which probably costs a few hp.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads