200HP OX66 Compression Numbers

[M-D]

I am looking at a boat with a mid 2000's Yamaha on it, has just over 300 hours. I am being told the compression is 90psi on all cylinders.
I know next to nothing about Yamaha motors but have always heard the OX66 motors were great.
Guessing they are not very fuel efficient like the HPDI motors are?

Can you guys who are in the know about this engine tell me what the compression number range should be?
Anything else I should be asking about or looking for?
Could a readout of hours at RPM's be obtained from this motor?

[CJ1]

As long as all cylinders are within 10% it is good. But I would do the test myself. His gauge could be off a bit and that is why the 90 psi reading but it is still acceptable. If they are propped correctly they are roughly 10-20% less than a HPDI. No on the hours and RPM's. Ask about 02 sensor cleaning and or replacement, low pressure fuel pumps serviced or replaced, complete filter service including VST tank. Lower unit service, should be done at least every year, pressure test lower unit, prop shaft straight. General condition usually says how it was taken care of. What fuel does the p/o use. ect ect. CJ

[slotcarracr]

Do a leak down to get a better idea what is going on