Mark B's comment got me on the right track to plunge in. The front cut needs to be as close to the front as you can get, right behind the stake pocket strip. As the wheelbase is 114 on the s/b vs 122 on the l/b, eight inches need to come out on the front cut. With the difference in box length being 20in, and considering the 8in taken from the front, the remaining 12 inches need to come out of the rear section; the rear cut being as far back as you can get it. No messin' with the wheel opening a-tall.
The other project is a conversion from a series lll to a series ll short land rover, ending up with a slightly different powertrain than stock.