i didn't use the bds stuff i made my crossmember and my link bars. my high angle flex ends came from ballistic fabrication http://www.ballisticfabrication.com/

well the easiest way to straight axle your rig would be to get the BDS long arm crossmember for an xj
Part # direct from BDS site.

014654 XJ 6.5" Crossmember Kit 1 of 3 311.53
014653 XJ 6.5" Long Arm Main Box Kit 855.03

for the rear just flip it under the leafs, 4" lift blocks and make some longer shackles
the front you should use an astro van steering box (saginaw) as well as the 4" drop pitman from a jeep, there will be lots of cutting, grinding, and welding as you will need to make coil pockets and relocate your shock mounts for streetability extend your swaybar rods in the back and in the front you will need to move the swaybar forward and make custom rods.