Tire Size Options with Required Suspension Lift

Two friends who own GT400's: 1. 1996 Chevrolet K1500 4WD Suburban; and 2. 1999 Chevrolet K1500 4WD Suburban. They are wondering about options for larger tires corresponding suspension lifts. Specifically, they are looking at the following three tire sizes: 1. 255/75R-17; 2. 285/70R-17; and 3. 285/75R-17. QUESTIONS: 1. What suspension lift is required for each of these three tire sizes? 2. Will a 4" suspension lift work for any OR all of the three tire sizes? 3. Is any inner or outer fender well trimming required for these three tire sizes and a 4" suspension lift? 4. Is a body lift required in combination with the 4" suspension lift? If so, 1" or 2" body lift? 5. Are torsion bars and or drive shaft modifications required? 6. Any other modifications required for the above mentioned tire sizes and 4" suspension lift?