They are a great car if you're not concerned about interior space, and really do well on fuel with good power.
The original head has some issues, if overheated or overstressed it can crack. Check the casting number on the head
http://www.peachparts.com/shopforum/showthread.php?t=289965 and be sure that it doesn't have oil in the coolant or coolant in the oil.
Rust in the rockers is another thing to watch, and in the door bottoms.
It's a pretty easy car to own, not much fails and there are so many of the gas version around that used parts are easy to find. With the original 2.65:1 differential and an overdrive it should turn pretty low RPMs on the highway, and great mileage. Mine (with the original automatic trans) regularly got mid-30s on the highway.