On the 110 build I am doing now that is what I did, use a regular Disco axle. The driveshaft will have to be lengthened. Parts are easier to source and you can easily replace the third if you ever have any problems. The salisbury is like a Dana 60 where you have to take everything out of the back. The pumpkin on the Sals is stronger but a cap, diff guard, on a regular axle seems to be fine. Indeed the axle on the sals is larger but I do not think as strong as a HD shaft in a regular axle. The outside tubes on the sals seem to be the same dimensions as the regular axle. You can also make the 110 lower spring mount plate for the regular axle or purchase them.
Land Rover 110