Welcome to the Club, Mike. To check I'd say you're looking at rust primarily, the undersides of these cars have a tendency to rot if they're parked on/over a moist area (grass in particular).
I once planned to buy a 300M with only 42k miles that was in excellent condition inside and exterior paint-wise, but the underside was totally rotted away.
Otherwise things to check are brake lines, exhaust, gas tank straps, shocks, struts, etc.
Once you get it in your possession it will require a review of the cooling system, particularly the water pump and timing belt, as those are to be done every 7 years.
2017-2021 Club Vice President.
2002 Dodge Intrepid ES. || 2004 Chrysler 300M Special. || 2009 Dodge Ram SLT.
1969 Plymouth Satellite Wagon. || 1969 Dodge Coronet 440 Coupe.
Ashley's: 2017 Ford Fusion Energi. || Mom's: 2003 Chrysler 300M. 40k!
Past: 2001 Intrepid SE. || 2001 Concorde LXi. || 2002 300M Pro Am. || 2004 300M Special.