Matt:
take a look at the top of the Ask Bud forum for many pdf's to download.
I've also attached a "Survey form" source unknown that may help with your pre-survey examination.
As for "weak spots" in the vessel - a lot depends on your sailing plans. If you are heading out around the world vs a day sailor in protected waters will determine the scope of your probable refit. Since these boats are 40+ years old I suspect that most of the hardware/systems will need examination.
What you can ask about are:
Engine/transmission condition and does the engine have a heat exchanger or is it salt water cooled.
Are the decks covered with teak if so check condition of the teak and the deck below for soft spots ie possible rotting plywood core.
Bowsprit & boomkins - usually made of wood looking for soft spots in the wood.
Sail condition, hull condition - when hauled out last etc.
Does the cabin smell of diesel or mildew / moisture or sewer gas.
HTH
Jay Bietz