I installed the rear disc kit from Cape. It comes complete with everything you need, whereas the Dennis Welch kit leaves many parts for you to make yourself. Not really my idea of fun.
The Cape kit is pretty well sorted and gives you a just good enough e-brake to pass the 10% grade test for the MOT here in HK.
I love the rear kit on the BJ8 and has definitely improved the total balance of braking on the vehicle. The car stops very well, but the rears never lock first, so it's nicely balanced.