Welcome to the club. Gray and black is a very classy combo. If I ever decide to respray mine it would be in some shade of gray. As to the headliner, very few owners have the time or patience to replace said saggy liner, from what I've read it's a very involved process.
I recently experimented with a can of hood insulation glue to tack up my saggy rear liner. Good results so far. Have more to do yet.
Good luck with the ride.

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1981 240d
Newport,RI