Westy:
Besides stemming from the V8 crowd you must also be from the midwest or some other rustbelt place: These cars aren't supposed to rust, especially NEVER in CA. They have a galvanized body starting in 76, if I remember right, and they don't have body seams like a dodge van either. The only thing you may find is some bubbling under the front 'smile' where there is an ungalvanized piece hidden. So, while we all are happy that the car is rust free, it isn't anything special.
Don't fall in love, remember!
The car won't pass smog if it runs this rich, even with a good cat installed. I'd just tell the guy you buy it if he fixes the smog and the rather obvious rich-run-problem which goes hand in hand.
A/C is marginal on these cars, even when it works. I think you can beef it up with aftermarket parts if needed. I'd ditch it, unless you are travelling the central valley frequently. It's a targa! Take the top off...
If it doesn't work out, just swap in a 289. It will be much faster down the straights.
George