Tips on inspecting/buying a 40 year old car?

Thanks for the responses, good stuff here.

That's a pretty good tip about driving behind - I'd forgotten about that one.
I will certainly take a very close look everywhere inside and out and under for rust on the body.

I will say this: I replaced my master cylinder and brake booster with brand new parts on my Duster and the master cylinder is already rusty looking only 2 months later!

I talked to the guy for quite a while just now and he was pretty nice. He was honest about some "small drips" from the transmission. I'm guessing it needs a seal replaced (probably dried up, like Geof mentioned above).

Also, he said he has complete records and offered to put me in touch with the service station that has done all his work.