I don't think that tire size should cause a problem with the amount of lift you have. I'm running 265/70R17 tires on my unlifted SR5 with no rubbing issues.
I am looking into the Cornfed 3/2 lift. Since you have the lift I'm looking into, I have a couple questions. Does the rear end look lower than the front when you are standing off to the side of the vehicle? Does the running board (if you have one) tilt front, back, or is it level?
Today I jacked up my vehicle measuring a 3/2 lift to anticipate what it would look like. After raising three inches measured at the front wheel well and 2 inches at the rear, the rear seemed a bit low. Could be something about the way I had it jacked, but just wondering what others experience has been. I would prefer either a level look or to preserve a bit of the "rake". Don't like the lower rear end look, which I had plenty of with my previous 94 4Runner.