A typical 'stock' 1968 or 1969 '383 Road Runner' with 3.55 Gears would run 14.75's @ 97 MPH.
That '383 Stage 1' upper engine upgrade would knock a good 1/2 second {.50 } off of the Elapsed Time, and get the #3450 lb. {Shipping Weight} '383 Road Runner' down into the 14.20's @ 100 MPH.
Horsepower Gain.......+ 40 HP over Stock
As for Total Horsepower, the 383/335 HP was over-rated by at least 30 HP from the factory, as it was much closer to the 300 HP range.