the jag rear end is designed to work really well with in a small range. As soon as you start going beyond that range they're awful.
the outer-end of the lower arm should rarely travel to a point higher than the stock height of outer-end of the upper arm, and vise-versa.
Even the hotrod guys over here have loads of trouble when they try to get their cars very low with them handling like shit, most have ditched the jag stuff in favour of other custom setups.
The guys that fit them into Ford Pops with drag racing monster tyres in the rear have the opposite conditions, the alignment is too high and they too handle like shit (except in a straight line)
A lot of people try to strip the jag setup of the lateral bars, then they're even worse ! LOL...