Do I smell a free drink in here?
Mmmm, my favourite type
Whatever you get, make sure it's had the cams out and the rockers inspected recently - or budget for some replacements! Ask the owner to start it for you and watch to see whether he revs it etc before it gets warm. If he does and the cams haven't been out - walk away, there's plenty more.
For that advice, I charge a LARGE glass of Wolf Blass Yellow Label Cab Sauv.
Or two ...