A little hint. After you switch over to GP shift, with the stock linkage, you will notice that the shift rod needs a LOT of adjustment. I like to put my pedal up fairly high so it's easy to get my foot underneath it, as well as making it easy to click off a clutchless upshift while hanging off the right side of the bike.
To get the pedal high, I just adjusted the shifter so that when it is pressed all the way down, i.e. it's farthest point during a shift, the knob JUST clears the frame.