Just trying to get an idea of what a car might be worth. My sister has owned the car for 25+ years and its been tucked in the barn. When she bought it years ago, they pulled the carpet and interior, cleaned it and tucked it away (I would suspect my brother-in-law oiled the quarters...farmer). I know it needs rear quarter work. It was a numbers matching 383-auto with air grabber (dual scoop), bench seat, Orange car. She has the build sheet, but recollection is that the fender tag is AWOL. 383 is out of the car and it has another 440 or 383 stuffed in it. Was running and driving when she brought it home long, long ago. Barn is getting worked on and it is finally getting extracted. I have not seen it since it was put in the barn years ago. She has finally come to the realization that she is never going to do anything with it. I will know more when it gets drug out, but to the best of my knowledge, floors and trunk are/were good. Once its out I will know more. Someone already expressed interest in it but, I have no clue where to even think about pricing a project car these days. Any general thoughts...(and no...I don't have any pictures yet).

If it's been in a dirt-floor barn that long, you should take a good look at the underside, any rodent damage, whether the FT and/or original 383 is around somewhere.
A thorough cleaning - though the barn-find crowd largely seems to prefer filth - is something I'd do, for several reasons.
I'll GUESS somewhere around $15,000 if it's pretty complete and has good panels except for the lower quarters, but needs cosmetics & mechanical work.
Look at Ebay "completed auctions" for similar '70 Bee projects, if there are any.
Orange, N96 & Broadcast Sheet are pluses, and having its original 383 would be significant. Bench & AT are generally not pluses in the marketplace, though they have their advocates.
I'll stay out of the FT debate, but missing it would bug me personally.
'70 Coronets are...let's say, not everyone's cup of tea; but they're also not falling out of trees, right ?

Besides what Topside noted: condition of the grilles, front bumper fillers, trunk lid, fenders, hood and rear bumper are all critical. These items are more scarce than an equivalent 1970 Road Runner (maybe not the trunk lid..). Grilles are reproduced and good, but costly. The reproduction fillers are junk. Fenders and hood are very hard and costly to locate good replacements. Rear bumpers are very hard to locate as well. These components will drive the value even more so than usual, IMO. Without pictures, considering what's been stated here, I'd say 15-19k if solid and complete.