Hey countryboy. I also just bought a 91 burban. Just got historic tags for it yesterday, and finished replacing the exhaust from the catalytic converter on back.
Luckily, my interior is in beautiful shape for a 22 y/o truck. I do need to get the seatbelts. I'm guessing someone put in racing harness style belts, then removed them before selling to the prior owner. Other than that, and the normal vinyl dash peeling, the interior looks like a 2 year old car.
I bought it with a 4 to 6" lift (im leaning on 6", because she is TALL), and brand new 35" BFG KM2 mud terrain tires. It totally changes the truck from 'soccer mom-mobile' to a 'mud beast', especially if you have rear positraction (factory limited slip). Just be aware, that you will probably need some kind of side steps with a 4 or 6" lift and 35's. It's not all that easy for me to get into and I'm 6' tall. My 5' 9" fiancee actually needs help getting into it, lol, so steps are going to be my first addition.