If you do buy it and plan on keeping the stock 2.8, replace the pickup coil under the distributor along with your first tune up. You'll be happy down the road when your car isn't having random, untraceable ignition issues. And as Patrick said, check out the ICM to make sure it, and the wires leading to and from it, aren't fried.
Other than that, the only thing I can think of is making sure the exhaust manifolds aren't cracked, especially the one right by the rear window glass. When GM performed one of their recalls they removed the weatherstrip from under the rear window to allow more heat to escape the engine bay. Consequently, the hot manilfold directly below is prone to cracking when cold rain water pours on it. Think of it as putting a hot light bulb in ice water. If the manifold is cracked and has never been removed, there's a pretty good chance you'll have to remove the heads to get the bolts out to replace it. You may have better luck being in Arizona but nearly 30 years of being bolted on there will make those things a huge pain to take off.
All of my advice is based on learning things the hard way.
Good luck with your purchase!