Are you converting to disc front brakes? If so, you may want to reconsider the booster, manual disc brakes do not perform very well on a truck.
To answer your question, if you are converting to a split system then the 1" m/c should be ok.
Essentialy you have 2 1" m/c's, one for the front and one for the rear. If not, then go for a larger m/c, thats what GM did on their larger trucks for more stopping power.
