Dave,
During your decision-making process, consider that the Victor (not Victor Jr.) is slightly taller than the Performer. You need to also get a different air cleaner or modify your existing one to fit under the hood.
Summit has the correct Victor
http://store.summitracing.com/partde...5&autoview=sku here.
My 496FE with 9.4:1 compression was dynoed at 609 HP with the ported Victor (about $450 for the porting and about $550 for the manifold). I replaced the Victor with the Performer and the car didn't "feel" as fast - I could definitely tell the difference. My SOP "dyno" test is how easily the rear tires light up by gassing it in second gear. The tires spin much more with the Victor.
The Victor changes the "look" of the engine from a street rod engine to a race engine also.
Food for thought.
Brian