Greg,
Recommend get a different set of eyes during the annual. It is usually a good idea to have someone you select look the airplane over. Someone who is about to sell his airplane is not motivated to spend much money getting a good annual completed - just enough to get signed off is usually the rule of thumb.
The normal procedure for an annual is for the mechanic to open the airplane up, so to speak, so that a full inspection can be made. Once that is done and the "squawks" are noted, the needed repairs are made. While the airplane is open, during the inspection phase, is a good time for your mechanic to have a look at the logbooks and the airplane.
That allows you to get your own squawk list and, if you decide to buy the airplane, to reach an agreement with the seller on price knowing that all those squawks have to be repaired to your satisfaction. Thus, you get an inspection that you can reasonably trust, the squawks worked off and an annual inspection completed.
Nevertheless, one working rule of thumb is to set aside about 1/4 of the purchase price for things that are going to break in the first year (Murphy's law, no matter how well the annual inspection was done) and to make the add-ons and changes you find that you want to make - such as shoulder harnesses, if it doesn't have them, radio upgrades, etc.
Best of luck - I've got a soft spot for the '68 model; it's what I got my Private, Commercial and CFI in.
Warmest regards,
Rick
