Yeah, body lifts are like ~$100, but with a 1989 you'll probably need to replace the body mount bushings as well, so thats another $80 or so...
I have 31x10.50 tires on my 88 bronco2, on the stock rims, and when the suspension bottoms out in the back, they rub on the inside of the tire well, and they rub the sway bar (which I have since pulled out) when you turn the tires all the way on the front. And the tires are pretty worn out... A mud tire with big tread blocks would be way too much.
Alternatively you can replace the shackle (belltech 6400, or comparable model) or leaf springs (Explorer springs), or add blocks on the rear to gain a bit of suspension lift... Although I would not do blocks until you've exhausted other options like leafs and shackles.
Also, You probably want to check the condition of your spring hangers (the things the mount the leafs to the frame) as they are prone to needing replacement, especially the back ones.