Was wondering this recently too and my thinking is that it will fit fine. You'll need a different wishbone tie too but they normally come with the wishbones as a pair, I think there is one on eBay right now for £100.
Anti roll bar plus xj8 monostrut instead of individual diff struts is a huuuuge upgrade and completely transforms how the car handles at the back, can highly recommend it.
Not an easy job either, lots of heavy and award stuffs to undo and handle but we'll worth it in the end.
1997, 4.0 LWB X300 - Unlucky car but still a daily driver.
1988, 3.6S XJS - Never ending restoration project.
1994, 3.2S X300 - Accident damaged, October 2015. Gone!
1994, 3.2S XJ40 - Long gone.