Yep, they were the high compression ones, ran very strong.
At my brother's encouragement, my Dad bought a real sleeper for my Mom. It was a 1969 LTD, ugly green 4 door, but it had a 429 4bbl. Car would not launch, but on the highway it was a menace! With the 273 rear it would bury the 120 MPH speedometer in 2nd (shifting automatically). The over mufflered engine would just whistle like a jet, and there would be a panicked look on the driver of the hot rod next to you!
IIRC, it had 11:1 compression ratio.