I picked up a Mark 2 several months ago.
So far, all the rust is surface.
Paint is in need of work (and doing the touch-up, preservation now), interior new, lots of other stuff "done".
Check on getting the paint work done.
Around here, almost 3 months of looking, NObody wants to touch a Jaguar.
The "best" price so far is $5K.
Figure that into your calculations.
Interior "kits" are what, $4500?
I paid three grand for mine, drove it home, and other than some days when new parts were en-route, it has been driven every day.
You need to look at not only value of the car on the open market, but what it's going to cost to bring it up to the same level as those for sale.
There was a 2.4L MK2, RHD, OD and wires, bare metal, you paint, for $2K locally.
That should give you some idea of where the value lies.
Add in chrome work, so let's say the car is worth, open market $20K for a really nice one.
Deduct $10K for paint and interior.
Another $4K for chrome (that stuff ain't cheap!).
Figure any mechanicals and rubber, and you're down to $3K to $4K.
And that's if you do the work!
Add in an upholstery shop to install your interior, whoa.....
Take it to a Jaguar shop to have mechanicals done?
Factor that in, how much does he want to pay you to haul it off?
Granted, that's a spread.
You've seen it, I haven't, but the pricing on the car has to be somewhere between $3K and maybe $8K.
Don't make an offer.
You will be too high, which he will accept and you will kick yourself over, or too low and upset him.
Let him open the bid.
Work up or down from there.