I have use the "normal" cone-shaped urethane bump stops from Jamco. They can be cut down for additional travel, if desired, but the "bump" is sharper the shorter they are.
I got a set from Jamco with my disc brake kit however the bolt is not long enough. I have looked around and my a-arms take a longer then usual bolt than the typical bolts on bump stops. I have seen some that take a bolt instead of coming with it embedded. I am looking at that as an option as well.