You would have to extend the outer shackle mounts as well if you aren't using offset pins on the leaf springs. Seems like the shackle mounts moving further from the tire would make the approach, breakover, and departure angles worse.
In theory, it should give you a better ride and more flex. However, it is already possible to have a good ride and great flex with a quality leaf spring setup using the stock spring mounts.
'93 YJ, 4.0, AX15, Aussie locked D30/open 8.8, 4.10s, 2.5 OME lift, 31s...