I also completely rebuilt a 1988 XJ40 in the last 2 years.
I did this in Estonia...
I am afraid the work was mostly quite poor quality, so it involved a lot of changing workshops and complaining.
I'm sorry I don't speak polish, but I did the work because it was a car which belonged to Martin Brundle the F1 and Le Mans Driver.ble
The car was given to him by the factory for the Le mans 1988 drive.
I have a workshop specialised in Jaguars in Estonia, so I was able to supply all the parts from stock.
It needed:-
4 doors
Boot
2 sills and 2 rear wings
2 front wings
New engine
New rear axle.
as you can see, not much of the original car remains!