You won't necessarily have valve recession, but you won't know until you pull the heads. I agree with the consensus to pull the engine for a few reasons. One is the ease of working on it at good angles. Next is you don't want to risk denting/scraping the body while maneuvering 60# heads around. And finally, you can get a good look at everything while the heads are off at the machine shop, and determine whether or not to do more.

If you don't know of a good machine shop that knows Pontiacs, find one now. And buy/beg/borrow that leakdown tester and an air compressor to find out what you have to work with. It can't diagnose bearing or cam issues but it will help check rings and valves.

You can expect the cam and timing chain to be ready for replacement. The timing chain may have caused the overheating issue in the first place. That is easily done with the engine out.