Re: XJ Seats the final answer: benches
Bench seats from a Comanche will work - use your original pedestals, drill out the rivets needed to bolt up into the Comanche frame. The seat adjuster lever will need to be bent slightly to operate - but since the seat cushion is slightly offset, it hits the B pillar anyway and will need more work to go back all the way.
Doing this with a full console means more cover up work, fabbing, and the loss of the tunnel mounted handbrake, which is a whole 'nother project to install the underdash type. Doubtful it will pass state inspection with no brake.
The console parts are modular, short or long, and you can swap the panels from one to the other - or scavenge them that way at the junk yard.
Seat belts can be added for the very short center position, will probably need longer bolts to secure all the ends, and no doubt probably not meet the OEM design strengthfor the anchors. At least your originals will slip right up and work no problem.
The spun bonded backing on the bench seat back is fragile and will not survive long term use, requiring a custom fix.
If you later remove it, use the bench seat in your garage against the wall - so it won't tip over. The base is too short for freestanding. I just may hang it from a left over garden swing stand for the ultimate redneck deck furniture.
Just a'swangin . . .