did you have the heads retested after the chamber mods?

if it has enough valve spring to reach peak power before any valvetrain unhappiness sets in, i'd be looking for 630-640 on our dyno.....possibly more, depending on what rpm the peak occurs.

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