here is the NHRA factor page. Used to be the NHRA published the factory shipping weight and then adjusted the horsepower for an engine. Now, they adjust the "factor" wiich is the shipping weight divided by the horsepower. So now you cannot multiply back to find the shipping weight....cause they fiddled with the numbers. But it does show some relative positions for a car line.....like the difference between a 150 and a 210 and a BelAir
http://www.nhra.com/tech_specs/classification/