The self leveling rear suspension can be eliminated. The red flag to me on this car would the "wiring redone". What was redone and why at such low mileage?
I've owned three e28s which share the same chassis as the e24 and they're rock solid. Most parts are cheap and they're easy to work on. There is a HUGE knowledge base at
http://mye28.com and those guys can pretty much answer any question about the e28 & e24 you might have.