Don't get a shackle reversal unless you need it. And there aren't many reasons why you would need it. In some cases they are better on road. In almost all cases they are not as good off road. Let me explain.
I once drove a flat fender jeep that had terrible wonder on road (it didn't have a shackle reversal). We weren't sure where the free play was but for the sake of discussion lets say it was in the front shackle bushings. With the shackles in front, if their bushings are loose the leaf springs may not always be pointing exactly strait ahead. With the steering linkages also mounted up front this can create a looseness in the steering. I think this jeep would have drove better on road with a shackle reversal. Why? If the front of the springs were mounted more solidly (without shackles) then the steering linkages would work better. The steering linkages are in front of the axle and as they push to steer the front wheels they work much better if the front of the axle is very solid. A better solution would be to fix the loose shackles or whatever has the slop.
Shackle reversals are worse off road because they work against the 4 wheel drive. Lets say one of your front tires is up against a rock and you give it some gas. The front tire will try to drive forward as it goes up over the rock. That motion is normal with a standard leaf spring. On the other hand if you have a shackle reversal the front tires would want to go back as they go up.
That's an important difference.
With a shackle reversal the front tires go back as the suspension compresses. The previous owner of my Jeep installed a shackle reversal and that has lead to many other necessary modifications. BajaEdition has made some good points. For one you will
need a long travel drive shaft up front if you have a shackle reversal. If you don't then expect your
Transfer Case to be your bump stop. I know of an off-road mechanic that has seen many smashed transfer cases due to a shackle reversal. The front axle goes back as you hit a bump and if the drive shaft doesn't have enough travel it smashes through the
Transfer Case . If your drive shaft has enough travel then, as BajaEdition pointed out you bulldoze over it because the wheel can move back. This is one advantage to the shackle reversal off road, especially if you hit a rock faster than you should.
Another problem I saw on my jeep was the front tires move back into my fender as the suspension compresses. It would have been better to mount the springs an inch farther forward when installing a shackle reversal.
I am not a fan of shackle reversals and I would
strongly recommend against it.