Well, not to be blunt but we folks in the South are usually like that. If you're going to be offering XJ13 kits you need to have that transaxle all sorted out before I pony my cash up. At any rate, the link I found for XJS conversions can easily be found on Google and is:
http://www.5speeds.com
And
http://www.5speeds.com/v12kit.html
and
http://www.5speeds.com/v12bell.html
Certainly this piece could be adapted to mate with a transaxle, the hard part is done. Seems I remember, but don't know, that Jaguar used turbo 400s in the auto cars, so there are plently of conversions for these around. Should be a fairly easy thing.
So, when you making kits available?
R