Crank the torsion bars up one inch, add a longer shackle on the rear springs and put a two inch body lift on it.
Before you do anything, get the truck "crossed up" in a ditch so that it'll teeter on one front and one rear wheel. This will enable you to get out and look and determine exactly how much clearance you actually have with your current tires.
Next you need to actually measure the height of the tires you intend to install. This will allow you to calculate the amount of lift you need. I would put 33's on it and call it good. 35's will require numerically higher ring and pinions, anyone who says different is FOS, unless the truck came from the factory with some sort of low-geared tow package, which I seriously doubt. EVERY increase in tire size increases the likelyhood of driveline failure off road, IE, U-joint/CV, output shaft etc. You want enough tire and no more.
Also, if you determine that sheet metal/fender is the limitation, have at it with a sawsall and install plastic fender flares.
