The SD-455 was an option on TA's in the early 70's (only 73 and 74 I believe)
During 73 and 74 production, Pontiac only made 1296 Super Duty cars.
it came with:
800 cfm Q-jet, 4 bolt mains, forged rods, TRW forged pistons, provision for dry-sump lubrication, a round port low compression head, dual exhaust and 290 net horsepower @ 4000 rpm.
Basically all the things you would do to a standard 455 to make it a real good motor.
The bore, stroke and rods are the same, just comes factory fitted with performance lower end, would just need a decent cam and intake and a little head work to make a fire breathing beast.