Here is what I've been paying for things:
- Carpet Kit (GAT) $829
- Seat pads (GAT) $1300
- "Old timer leather" interior (KHM) $4500
- Insulation that isn't made of guano (Resonix) $1600~
- New underdash panels, parcel panels, brake fluid reservoir, kick panels, washer pump, washer fluid reservoir (Authentic Classics) $1200~
- Transmission bushings kit (you will want to replace this, definitely!) (forget where I got it) idk like $120~
- Complete Cocomat Set (gotta be cool) (Cocomats.com) $800~
- Reproduction Euro headlights $1200
- New fancy radiator $600
Then there's all the maintenance items for you. I don't know what all new hoses, wiring, etc might cost. But that's an opportunity to do things well and right, say with braided hoses and all that. Who knows about the condition of your brakes. New tires of course, like good Vredesteins (no need to buy the overpriced and stupid Cokers) will cost you $875.75 for 5 185HR-14 Vredestein Sprint Classics delivered to you.
So there you go, I've paid 13k in largely maintenance and cosmetic items (I hate yellowed plastic). The car was fine and drove fine before. I paid about $49k for my car in November, and it had been repainted very recently.
Then there's the paint. If YOU disassemble it, assuming there's no body work or anything to do, it should be around $15k. If someone else does it, expect considerably more, closer to Teahead's estimate. Also a lot of this is location dependent.
Chrome one can spend a fortune on if you want to. But you said it is fine. I'd leave it alone for now.
Drivetrain rebuild is 10k for the motor from Metric or Noel's. Transmission, call it 5000-6000. Because monkeying around always happens, expect closer to Teahead's estimate of 20k. Also, a lot of this is dependent on you removing and draining and shipping things rather than paying a guy to do it.
In my mind, I picture this car being like this, but with crappy paint:
https://bringatrailer.com/listing/1971-mercedes-benz-280sl-60/I like 30k. I'd expect 60k+ in costs to have something you're proud of. Add on more if you want to do things like convert the transmission (assuming this is a manual, about $1500 for a Getrag kit and $800 for a 265/6 or you could be like me with a 265/5 for 3-4k), change the rear end (a couple grand depending), new springs and shocks (about $1500 or currently $2300 for a Mechatronik kit if you want to be fancier!), $1000-$1500 for non-boat anchor wheels, and... oh, I forgot, how is the wood on the inside? May need to refinish. Tack on more money. Teahead's $15k-$20k is looking better, especially if you are having someone else do all this. If you need to rebuild the rear axle and replace things like rubber boots, add another few k. Really good restored 280SLs go for between 100k-120k depending on the day, some of the options, pictures, color combo, etc.
Then there's your time, regardless if you have someone do everything.
I actually don't think this is an inappropriate car for BaT. Remember, it's "bring a trailer," not RM Sotheby's. If you're totally honest about everything it needs with 300+ pictures and aren't obfuscating anything, you can do just fine. It's people doing hinky stuff that get destroyed.