The Mighty 396...NOT!
A stock 70 383 Super Bee/RR is a 14 second car.
Minor mods and/or a good tune can make it a high 13 second car as well.
(and that's a 9.5:1 motor still "rated" at 335)
I've always wondered why the 301 pontiac was called a 4.9 but the 302 ford was a 5.0.
Seems there's a lot of leeway in the conversion, for marketing purposes.