[Mike Carr]

I believe, for GT classes, you take "the shipping weight of the car with the heaviest gasoline V-8 engine available".

As for hoods, if the engine used came available with ram-air, the car can use it in GT. Otherwise, no, or hood must be blocked off.

Example A: 1995 Firebird with 2000 LS-1 engine for, say, GT/BA. Ram-air is OK.
Example B: '95 Firebird with '76 Corvette 350. Flat hood, or scoops must be blocked.

So, a '68 Firebird could use dual '68 ram air hood in Example A, but not Example B (or blocked off).

Not sure about same year car/engine. I've seen racers claim a '95 Camaro/'95 LT-1 in SS/IA as a '96 Camaro/'95 LT-1 and run GT/FA.