Ask the surveyor to inspect the chainplates as best they can.
Unfortunately they are glassed in and behind the cabin timber lining, so it's virtually impossible to inspect unless you start pulling the boat apart. You can however partially inspect the forward inner chainplates from inside the forward cabin port clothes locker and inside the head starboard compartment. They will be glassed over, but the surveyor should be able to see any obvious signs of corrosion where they enter the glass.
We had a chain plate let go due to crevice corrosion only 6 months after purchase. It's not a small job to replace and or repair.