Biggest issues with a spring over conversion are thus:
Axle wrap, With the springs under axle your leaf springs resist axle wrap imparted by the drivetrain when it loads. With the springs over the axle tube these load (the twisting force of the drive train) in on the opposite end of the lever so to speak. Instead of resisting axle wrap is adds to it. To save your springs and your pinion U joints a anti-wrap bar needs to be installed with a spring over, Such as the one available from SAM'S Offload.
There are some real advantages of a spring over, you gain a lot of lift from relatively flat stock springs that allows LOTS of movement and flex, Beware that you have enough shock travel and brake lines to take advantage of that flex AND enough fender well clearance.
Moving to the front axle, some real issues, Moving the springs perches over the axle is not as simple as it sounds, Although I have seen lots of ghetto hack jobs do just this. The issues arise in figuring out the proper caster angle so your steering returns to center Even if you manage to get the caster angle correct then you have some pretty creative problem solving figuring out steering issues in clearance around the drag link and its angle. There are a couple of solutions here.
MORE makes a bracket to move the axle ended of the drag link above the axle, although I have only seen this on a YJ
High steering which moves everything up in to correct geometry, with the benefit of being protective of the tie rod.
Cross over steering conversion which changes out everything.
NONE of these options is particularly cheap but they are the best solutions. A improper solution is a bunch of different drop pitman arms and bent tierods that are a hazard to yourself and anyone near you these might bandaid the steering issues but they are not safe or strong, DO NOT do the easy way out just because some hack has gotten away with "cheap" does not mean it is safe.
In addition to the steering and spring issues, take a look at your spring perch in particular CJ spring perches are not strong at the shackle end and the newest CJs are pushing 35-40 years old now. Those bend plates that the shackles tie into the frame are known to pull and break, consider slick rock spring hangers or a spring shackle reversal to address these. Beware that a spring shackle reversal adds some complications as the front axle will travel BACK and this limits clearance and tire size.
