Bubblemaker,
Ignore this post, because I know nothing about this kind of change, and I know nothing about that Jag front end.
Something to consider?: that Jag's "curb weight" was/is about 3,800 lbs; and, a 3100 would be about 4,800 lbs.
How do you intend to use your truck? As a car (people carrier) or as a truck (load carrier)? If you will be carrying full truck loads, will the Jag parts be safe/strong enough?
Good luck with your conversion. Let us know how you progress (links to photos would be nice).
