Actual ZL-1 Horsepower.

[GMH454]

Had the joy of a A/Prod Vette with crate L-88 several years ago. I asked the guy I bought it off about the horsepower and said his engine was built for torque, the engine builder had told him it was 550lbs.
It drove like it, at around 4800-5200 it would break the tyres loose (Big 10" racing wheels). That was not on the gear change but on accelerating up thru the rev range, in third that's around 130mph with a nice twitch just to make sure you are paying attention.
Junior Johnson once said "horsepower sells cars....torque wins races"
When Tonawonda (forgive the spelling ) closed the NCRS did a feature on it and asked the guys there what the L-88s dynoed at, they said around 510hp, on the engine stand.