What to look for when buying
My first suggestion would be to do a search on this forum for "What to look for" threads. You will get a listing of posts that tell you exactly what to be concerned about when buying a SC. There are specific areas such as head gaskets, ABS brakes, rocker rust, sagging doors, suspension issues, etc. The list goes on.
I'm very new to the SC lifestyle so take my comments with a grain of salt. I did do a lot of research here on this forum and elsewhere before buying my 89 SC two months ago. With that many miles, my concern would be head gaskets. If they were never changed, they could blow anytime. You should budget to replace them right away. Also, the ABS light is a concern. The ABS brake systems on these cars are expensive to repair back to factory spec. Or you could spend much less and replace it with a non-ABS system (ABS delete) if the repairs get deep into the ABS system. Do some searches here about 'ABS' and read up on the issues.
Are you mechanically inclined? Worked on cars all your life? Then a fixer upper may be the way to go. If your budget allows it might be beneficial to look for a nicer car that has had some of these major systems addressed by the previous owner so you only have to worry about the little (read less expensive) things that need repaired.
Anyway, that's my $0.02