[karlusmagnus]

Pics, pics, pics will help.
In the absence of that, lets see what you have

Sepia Brown 73.5 with 98k
No rust (this is a big if)
Original Paint (except for touchups where mentioned)
Tranny/Engine refresh 15k-20k miles ago w/paperwork
No sports seats
No tool kit
No H-1's
No fog/driving lights
Pretty good original interior
Fuchs

Non running / Needs clutch / fuel line refresh / oil line refresh / new tires / new battery
Interior will need refresh at some point (headliner getting a bit ratty, seats need upholstery, carpet original but may stand out if headliner/seats refreshed)
Steering wheel is/is not original?
I presume it is running, although you have stopped running it since oil-return issue. How long ago was that?
I presume that you do not have paper trail all the way back to original owner or of everything done to car over the years.
$10k would be a steal based upon what you have stated.
If it was running well, with oil pressure and fuel sorted, it should get you close to $20k. I mean it has original paint, with some touchup on hood/driver door. That is, if no rust.

Only thing is that Euro/Sterling are depressed compared to dollar, so you need someone in US to pay that. I would say that $15k would probably allow someone to put some cash into it and spend a bit on doing some upgrades, so that they would not be too much in the hole.

Still opinions are a dime a dozen. Why not put it up for sale, ask a price, post lots of pics as you seem intent on letting it go, and are not using it? Or wait until spring, fix little things in interim, get it running, and you can be more aggressive in your asking price.