I would never buy a Yami of that vintage without proof of them being done or compensated for doing them. Your talking $4K off of an arbitrary sales price on an expensive purchase.
The ONLY way to insure that the motors are corrosion free is to drop the powerheads. This issue does not go away for the seller. Unless they can prove it's been done knock off enough $$$ to cover it....or walk away.
Corrosion issue has been found in motors with a wide variation of hours. Again..... assume they need to be done, and negotiate it into purchase price. Don't waste the $$$ and effort on scoping them. You can thank me later.
If no record of exhausts being done assume the kits are needed and reflect that in your offer price. Don't even bother scoping them. ASAP after purchase go to a reputable Yami Cert mechanic and have them done. I did this with my 2005's with 480 hrs that ran like a top on sea trial and one motor...
I found everything your looking for off the cape. South Coast, Marion , Mattapoisett, Fairhaven, Dartmouth or Westport. All of the amenities with less expensive real estate and NO BRIDGES OR TRAFFIC!!