df--

3. "Cruise" speed: there wasn't any obvious way to figure out where to
maximize mileage (knotage?). She got up to 3800 RPM and 27kts
(according to fish finder) at WOT, and I've read that cruising speed is
about 65% of RPMs, but she seems to need 3000 RPM to plane, and then
we're only going 17-18 knots.

WayneB--
That engine should turn in the mid 4,000 range if everything is set up
properly and running right. Normal cruising RPMs are 3,200 to 3,400
RPM (about 70%).

df--

Along with the boat came all the paperwork dating back to 1977,
including shop manuals for the engine. The specs state 3800 to 4200 at
WOT. I'm sure they've managed to find a lot more RPM out of the 350
engine in the last 26 years.