According to the build sheet, my GTO originally had a 400 HO engine. Somewhere in it's life someone swaped it out for a 455.
Here is the engine as I got it:
Since then it has been rebuilt by Mike Zimmerman at Zimmerman racing:
Just a few detsails:
* Edelbrock Performer heads
* Edelbrock Performer intake
* Edelbrock 800cfm carb
*Dyno'ed at 535hp, 612 ft-lb torque