the two extra cylinders dont make that much of a difference though. The size of the block is relatively close to the size of a 3L block, although it is slightly wider, but its not like it is 1/3rd the width again, its only a couple inches difference. Theoretically it is possible I believe to fit the V8 in the contour engine compartment, albeit there would be a lot of cutting to the fenders, I am not sure if it would fit with the stock location of the strut towers so they may have to be trimmed and modified, plus it would require some changes to the subframe. But I think one of his biggest hurdles would be engine management. He would have to either swap a full wire harness, ECU, cluster, and a buncha other minor things from the SHO, or use a standalone. But then moving back to the rest of the stuff, he could transfer the ATX from the SHO (dunno why anyone would want to do that your gonna lose the 20 hp you would have over a 3L) or you could modify it to accept an MTX. The transmission though would be slightly offset from its original mounting position on the contour subframe, and the taurus subframe is to wide, so that means custom subframe. Then he would have to have new driveshafts made to make up for the offset.
Like several people have said before, nowhere near worth the cost. A 3L is nearly a direct swap, nets only slightly less power, and has enough aftermarket support to blow the doors off nearly any 3rd gen SHO.