As far as I know, and I'm pretty sure about this, but I don't think the Buick Regal came with a turbocharged V8 (only the V6 was turbocharged).
I would defiantly test drive it. Scrutinize it carefully. The fact that it is 25 years old and only has 43k miles on it. Most cars that age have well over 100,000 miles on them. The fact that it has so few miles on it might mean that there are a lot of problems. Also, Regals from that era are quite popular (many people like to convert regular Regals into GNXs). That means either there is something wrong with it or the person selling it doesn't know what the car could be worth in decent condition.