I had an 85' 242 LS. Twin small blocks. Running 23 inch cleavers on twin alpha drives that were NOT counter-rotating.
That boat boat in extremely light load would run 65 gps. When trimmed out for that last two mph, it chinewalked EVER so slightly. It was so slight it did little more than kind of jog your memory of watching the backs of hydros or something. Not even an annoyance of any kind. Just something you were barely aware of.
Got a feeling that counter-rotating drives would have made a big difference in that.
If you're going to achieve those speeds, yank those baby Bennett tabs off and put some K-Planes on that boat. At 75 or plus mph those Bennets are not going to stand up to the punishment, and if one goes at a bad time, you could be killed.
Hydraulic Steering is MANDATORY. Case Closed on that subject.
Other than that, I'd say go for it. Sure surprise a lot of boats....