So I am going along on plane, throttle at 85% just fine. No noise,
nothing. Suddenly, a loss of power as if I cut the throttle back. Cut
throttle back & checked gauges. Temp had spiked almost instantly to
240 plus. Shut down. Waited for tow.

Water pump changed, found seals etc and blades really screwed up
inside. Water test under load at full throttle: 2500 RPM's MAX !

Back on land, compression check: 4 Starboard Cylinders were 150 + but
all 4 port cylinders were 120-123. My mechanic says pull port head,
have machine shop check for warpage, leak test etc, clean, replace
gaskets and should be fine.

Question: Does this sound correct ? (replacing head gaskets will
improve power and solve problem caused by water pump overheating when
it went bad)

Is 150 on this engine acceptable ? What is "normal" or recommended on
new or used engines of this type. (stern drive merc v8 260 thunderbolt
ignition)

Thanks !!