As far as I know, not all that far, an S type V8 would likely bolt in.
With some mount fabrication Not all that hard. But, that is where the adventure begins. Namely, the electronics.
Whew, high adventure !!!
Now, an LS install is clearly charted and much help available.
Andrews’s Jaguar Specalties at the top . Not to disparage others. Johns cars, JTR, Sun Coast, etc.
My car has an older GM engine and transmission. I chose another vendor for personal reasons. Yet, when help was needed, Andrew was there.
My GM and LT1 have performed great. An LS1 would likely
do even better.