I have a 1990.
Ditto on the holding tank, I replace my aluminum tank with poly along with all the hoses. It's not small job by any means but straight forward. There is lots of information on the forum about doing it if you search.
Check and make sure your dinette table moves up and down. Mine had corrosion and is stuck in the up position. You should have a cushion that fits over the table when it is in the down position.
Check the windows for leaks, the boat is starting to age and they like to leak, I have replaced all my windows and hatches with new glass and seals.
It's not a new boat so just expect to need to start replacing odds and ends over time.. hot water heaters, battery chargers, seacocks/through hulls (due to age and corrosion) etc.. that kind of stuff.
Unless it has been updated all your lights will be incandescent, it's nice to have LED.
Ask how old the Standing Rigging is (ask for proof/reciepts). If it is in need of replacement it can be quite expensive and something you may not want to do yourself. Anything over 10-15 years old should be considered needing replacement and close to end of life. Get a quote to put that in your budget.
Old sails, still work and are ok, but can be out of shape and not give you the best sailing experience especially if you have any kind of furler on the mainsail.
Things that get neglected in engine compartment and too look for: Heat exchanger, thermostat, hoses, throttle cable, shifting cable and motor mounts. Find out when the last time the motor mounts were replaced. If it has a dripless shaft seal how old is it. (should be replace every 6 years). The 3GM is a great motor if taken care of.
Make sure your drive wheel doesn't have excess corrosion. Corrosion can build up due to where it is, especially around the drive stops. The drive cables should be checked as well.
How old are the Batteries?
Any leaks in or around the cockpit will show up in the plywood wall in the aft berthing and or the plywood shelves in the at lockers.
Not to scare you but things to look at and consider that may need attention if/when you take delivery.
Feel free to send me a message if you have any questions. I have had mine for over 2 years and there is not much of the boat I haven't touched to repair or upgrade.
Good luck and hope it goes well if you purchase. It's a great boat, fast, and easy to sail. I have thoroughly enjoyed mine.
Steve