If you are comfortable with the "reline issue", then I think the brake upgrade is not a concern.
Given that the "gold standard" of 4x4 have 17" rims, I think that should not be such an issue these days.
I had a 6.5 in a rangie years ago with the GM p/s pump, I never had a failure.
There are plenty of alternate pumps that fit the same brackets etc, so I don't understand what the problem is.
why carry the electric p/s pump, when you can carry a spare GM pump is something I have not come to grips with yet, given the weight and complexity issues.
My conversion is nearing the end, I've organised the trans cal which was my biggest challenge with the 6L90. Keen to get it on the road and start the tuning.