You will need a 2" body lift and the torsion bars adjusted to the maximum Z height. Plan on adding a spring lift or shackles to the rear.
I would suggest you look for 30x9.50-15 tires. Measure the fender opening. It is only 31" on the rear.
To get 31" tires you will have to select a "small" 31" tire and as rounded a sidewall lug as possible. Some trimming or massaging with a BFH will be required for the pinchweld at the rear of the front fender. Even then offroad you are going to rub.
You will need to stick with the stock wheel size and rear spacing. 7" wheel and 6" rearspacing. The tires will rub the frame, so building up the stops is needed.
Plan on installing the fullsize bump stops up front to keep from rubbing the top of the front fender.
You can add wheels with less rear spacing or wheel adapters to eliminate the frame rub. That will increase the scrub radius and fender interference becomes an issue.
Every change has a consequence. Decide what makes sense for you. There are tons of posts and many combinations. Happy searching!