The 428's were never installed in any 67-69 Firebirds, or 67-69 GTO's. There were a few dealers that did engine swaps, but those are extremely rare. You would need extensive documentation to prove that a dealer installed a 428 into your car when it was new. The 67 Firebird was only available with the OHC-6, 326, or 400.
The 428 is a pretty stout engine. Nearly all 428's had 4-bolt main caps, something that's desirable for the Pontiac guys trying to make massive power, using a Pontiac block. In stock form, the 428's are great runners. The 428 was produced between 1967-1969, and used in Grand Prix's, Bonnevilles, and Catalinas. None of the 428 powered cars had Ram Air.
