Dan, I was in the same boat, old tired flat springs, with the 2" BDS and shackle lift I gained about 4+". I first went with 4° shims for the rear axle but that was not enough the drive shaft angle was still off and the slip yoke was only engaged about an 1" or so. I went with the motor mount lift as I also did a 1" body lift so this aided with the radiator placement. I would still think you will need one or the other...
1987 YJ, 258, Weber 32/36, HEI, Custom Sound bar, Hardtop/Sun-rider/bikini tops, 2" Lift, 1/2" Boomerangs, 1" Body & MM Lift. 32x11.5x15 Copper STT's on Black Rock 950 Lobos w/4" backspacing, Still need Front Bumper and Seats.
My build thread: [url]http://www.jeepforum.com/forum/f12/my-very-slow-87-yj-build-thread-1137667/[/url]