shimming a front axle

I am having issues installing my front drive shaft in my truck right now. I was wondering how many degrees I can rotate the front axle with shims before the caster gets to fare out of whack and I wont be able to drive it on the street. I only drive it to and from bogs and the occasional trip to dairy queen. But I would like it to stay on the road at least!
Or would I be better to cut the C's and rotate them on the axle? How much caster do ya want if and when ya do this?
What do ya do with the studs and u-bolt plates if ya roll the axle?? pics would help!