Now for the meat of the post... the engine swap.
Done in about 18 continuous hours of work (24 if you include sleep) - we are amateurs after all.
I'll let the pictures speak for themselves, but here's a general overview:
The old engine was totally seized, so we couldn't rotate the crank to release the flexplate to torque converter bolts. We stripped down the old engine as best as we could to see if we could figure out what was causing it to seize. Note the headbolts are T60. Landrover sells a special tool (of course) but we got a set of extra long Torx sockets on Amazon ($16). You can see the epic carnage from cylinder 7 detonating in the block. I wonder what that must have sounded like while driving!
With the engine totally stripped, and new parts transferred over to our donor Jag block, we took the engine/transmission out as one unit. When it was out, it was clear to see the problem - the connecting rod in cylinder 7 had actually impacted through the side of the block (I didn't get a good picture of this). Some short work with a drill and chisel, and we had a very destroyed, but freely-spinning, engine block. Flexbplate bolts came off next, and then we put the transmission back in the car.
After building up the new engine on the stand, we realized that the Jag and Land Rover engines actually have two different sump designs. So we had to switch the oil sumps between engines. The only part that needed to be swapped over was the pickup tube - the sump otherwise bolts up. We did have to clean out the bits of piston chunks from the sump first, and the destroyed oil level sensor too...
The last challenge we faced was swapping the exhaust manifolds, because they are different between the Jag and Land Rover engines as well. It looks like they are mounted with a Torx bit, but it's in between T50 and T55. We thought we were stumped, but turns out an 8MM hex socket works just as well
I don't have any pics, because we were both pretty tired at this point, but we installed the new engine in the bay, mounted it to the trans, and starting hooking everything back up.