Congrats
Like any T-bird of the age look for rust in those rockers. The ground effects hide alot of rust. Also check the bottoms of the doors. Door pin bushing tend to wear out like all other T-Birds.
Head gaskets... like the N/A 3.8 these blow too. Any weird noises, coming for the SC, sometimes the snout seal leaks and the run low on oil and start to become loud. (SC oil from GM it is cheaper than Ford oil) (SAME STUFF TOO) If the SC nose is junk used ones run under $300.00 on ebay often. Motor mounts, they wear out and the filter is a pain to remove, when they get really bad the oil pan cracks, and wear out the PS hoses. Valve covers gaskets leak - usually just need tighten down a little bit 3FTLBS ONLY. Sometimes the valve cover get cracks in them too... so any major oil leak working it way down the engine look here.
AOD tranny suck. OD wear out in them quite often.
The older SC - 92 and back had a prehistoric abs unit, that is prone to some failure. The reman unit is now available (somewhere) I have heard around here that it is under 200.00 but I could be wrong about the price.
All of these things sound expensive, however these cars are not too bad all in all, I love my car, I've had it about 3 weeks now, and only drove it one time (to home). It's a 92, had some engine troubes and tranny troubles, but for under a grand who can complain.
You'll find that the SC is going to be a really step up from an LX. It has a lot of neat gadgets and gismos in the cars too.
Good luck in your search,
Tim