Hell of a long unit to fit into a series motor. I doubt that any of the mountings would work.
You would have to redesign the engine bay, probably have to fit an extra cross member, and fit some sort of top brace as well, not to mention a much bigger rad, and oil cooller for the box.
Would a Jag auto box mate to a transfer box? and if it could be made to, would the transfer box take the loading?
Series brakes certainly wouldn't be up to the job of handling the extra loads involved.
That said. There is a thread on another forum..V12 into a 110, though it has been running for a long time, could be worth a look, find out what problems he came up with.
Pete