During the survey and sea trial, we did run the engine through it's paces. We took her through the RPM range and compared oil pressure, temperature, and boat speeds with no major issues found. There is a discrepancy between actual RPMs and what is displayed on the tach since the owner changed out the alternator, but we didn't have the equipment to determine how much of a difference it was. Idle was also a bit low and needs to be adjusted a bit. We ran her at WOT for a good 10 minutes without any issues. The surveyor said there was some vibration, but it wasn't anything that raised any red flags with me. We checked for play in the cutlass bearing, and found none. There was very little smoke at any point during the run, even at startup.
We also took oil samples from the Perkins and the Genset, and both came back from Toromont Cat with no issues.
All of this in mind, I've been wondering if I actually NEED a mechanical survey. I'm still coming down in favor of yes, if for no other reason than my own peace of mind. I think what we did in the first survey will be enough to satisfy the bank and the insurance folks.