I spoke with the seller. He offered to put the car on rack to look underneath, give me the receipt books, run compression and leakdown, and take the car to a dealer for a PPI. Also offered to put a catalytic converter back on for CA emissions test, although I don't know whats involved with that. Seems like a decent guy. The last time I tried to buy an E28 the seller wouldnt agree to a dealer PPI so I walked.
Andrew, thanks for the connection to Adrian Pasternak (BMW CCA CVC Vice President). Sounds like he knows these cars well. I sent him an email hoping to arrange a time to take a look.
I'm hoping to get a new daily driver out of this. Ill share photos once I have them.
-David