I drive my original B3 blue 72 GSS Demon about once a month to keep it in shape.
It is just like Rhino said. It is slower than my six pack 71 is by the seat of the pants, But really they would have to be run side by side against each other to be fair as the six pack car has more gear, larger cam and and yet it still is alot of fun to drive.
I have lots of this stuff as I have collected a few extra parts and still have two out of the three GSS demon 340's still.
I may be able to help you with your questions.

I was told that my blue 72 is putting out about 450 hp.
It spins the tires easily on launch, and has run a best of 13.04 at 104mph with 3.91 gears and stock exhaust and tires.
I live in Orange City, Florida.
Grant Eaton 407-947-9005