I think the 265/70/17 will clear. I say I think because the 9" wheel width throws a wrench into my visualization. The offset on those wheels is good though. It'll keep the tires off the frame and sway bar.
It depends on where you are located but a dealership can do the work but will they? You can also look up reputable suspension shops in the area. I'd look for ones that specualize in 4wd and off-road. If you place the snap ring in the proper location for your desired ride height then the rest of the install is hard to screw up for a decent mechanic.