The boat in the 'Rumble on the River' video, is a std P18 of about '88, with a 2.4 200, also '88 (old 225) with stock lower unit, and at the time of the video, a stock ali 25" merc prop.
It would pull an honest 6200 rpm on flat water, indicating mid 70's. I reckon it was a true 70.
I never got to play with motor height, or different props, as the customer really just wanted it for skiing, and it did that job pretty well. So once rigged (twoz new), and tested (
) it went to the happy customer, and I only saw it for the odd service etc.