I really don't want to discourage you, but 6'-8" is pretty tall for a vintage Airstream. Only your husband will be able to determine if 'it works' for him. He's definitely going to have to duck to get in the doorway...and may have to stoop a bit inside. Also, the beds are pretty small...even my 6'-0" "stomach sleeper husband" has complained about the bed size in every Airstream we've had.
As far as cost/price - you may want to check out this "Price vs Condition
" website (Table A) for the value...depending on the actual condition it sounds like it is somewhere between 'As-Found
' and 'Average
' condition. Then there is the cost to replace/repair it (Table C) to get it to a suitable condition to camp in.
I would also double check your Subaru's towing capacity...I think they range 2,700-3,500 lbs. maximum depending on the year. A empty '63/'64 (we had
a '64) GlobeTrotter of that era is just about 2,890 lbs. - fully loaded (water, propane, personal contents) it's going to push those numbers.
There's a pretty active Airstream community in the Pacific Northwest - I know it's tough right now with Covid, but maybe you can get to a gathering to check out a bunch of trailers side-by-side to get a better feel for what options there are....6 hours is a full day's drive to go see something that may (most likely) be too small for you & too big for your tow vehicle.
Good luck in your search! I hope you can realize your dream...if not with this trailer, another one!