check oil, tire tread, brake pads, the under carriage, and overall feel of the car. So, honestly just make sure it feels right to you. If something doesn't seem right ask them about it.
Early tunes had #8 cylinder problems until aftermarket tunes were perfected. You can rent a compression gauge from Advance or Autozone for free. Remove spark plugs and check compression on all 8 cylinders you simply screw the gauge in each cylinder and crank to see how fast and how high compression is. It should be about the same on all cylinders.
The manual transmission is problematic. Row through all the gears at low and high RPM. Check for grinding. They are a little notchy in general from the factory.
Inspect suspension for aftermarket parts and check the bushings. Ask for oil change receipts. Look under engine, transmission, and differential pumpkin for leaks. Good luck. They're great cars.