P94 brushes will just act as a drag brake on a stock motor.....not a good mod.
You might be able to squeeze some more timing out of the endbell if you cut the tab off...every degree makes a difference.
Bearings won't make it any faster, but it will make it more efficient.....
Drilling the arm can work, but I would recommend making SURE the person doing it actually has a balancer....and the niftech one doesn't count as a balancer....
If you can go outlaw, have someone wind you a custom arm with bigger AWG wire...I've made them for people before....they are $35...