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 ?