some photos of your current setup would be nice. :thumbsup:
If you MJ is currently spring-under, then you just need newperches burned directly above them in spring-over configuration. There's no need to remove the originals, so you could still revert back to stock at any time.
Also, if the axle was NOT out of an MJ originally and was installed using aftermarket perches, then the bolt-on kit WILL NOT WORK. It is designed to use the stock MJ perches. The kit's pieces fit into the inside of the perches and uses them for both locating and for strength.