With the exception of poor approach and departure angles, these trucks already have quite good ground clearance as is. As my truck sits now with it's tiny 29" tires, it has more ground clearance then my father in law's stock Chevrolet Silverado 1500 4wd truck on stock 31" tires.
Heck even with it lowered about 3" in the front and 5-6" in the rear, it was quite capable on gravel roads, out in the fields and around the barn.
As low as the truck was it still had adequate ground clearance, everywhere except the long overhang at the rear bumper it would scrape at steep entrances.
Now then, for answers to what you are really talking about. I got tired of the lowered look after a while, mainly because I wanted it even lower, and didn't feel like dumping more money back into this particular truck to do it right. So I decided to go back up.
91extcab already laid out the basic idea of what I did, as he mentioned, be sure to get that alignment or you will wreck your new bigger tires.
I returned the rear to stock, and reindexed the front torsion bars up about 6" (probably 2.5-3" above stock, remember I was lowered before). Reindexing the torsion bars up is the exact reverse of the how-to for lowering the truck by doing this. Look at that how to, and the direction they tell you to turn them to go down, turn them the other way to go up.
That resulted in this:
That is still on my "little" tires, that are really only about 1/2" shorter than the stock 205/75R14s.
Then I added 205/80R16 Kumho Road Venture MTs. These come out to be 28.9"x8.1".
These are 2.8" taller than the stock 205/75R14, so by tire alone I gained 1.4" of ground clearance. My rearend is still stock, so that is the only clearance gained there, but at the front, by raising and leveling the front suspension I gained roughly 3" plus the 1.4" from the tires there.
The way my truck sits, my front end is about 1/2" higher than the rear, I plan to add longer shackles to gain about 1" of lift back there (to gain 1" of lift by shackles, you need 2" longer shackles). Remember that adding lift back there will gain you clearance at the frame and body, but the axle still sits in the same place. The only way to gain clearance at the axle and springs is to put bigger tires on. Also keep in mind that longer shackles in the rear will point the pinion angle up, you may need to shim it back down to compensate. Also longer shackles will alter the shackle angle, which has an effect on spring rate, though ever so slightly.
The same goes for body lifts, they will lift the body, but you are still limited by clearance at the frame, suspension and axle. What a body lift does do though, is allow even bigger tires to increase ground clearance, and also since the body is raised, your approach and departure angles are higher.
One downside to lifting by using the torsion bars (there is no other easy way without redesigning the suspension) is that you are still restricted by the stock range of travel. This means that by cranking the torsion bars, the control arms are angled farther down. This means that instead of riding in the middle of the travel range like stock, having plenty of movement up and down, now you have tons of compression room, but very little droop. This isn't really noticeable until you hit something like train tracks or anything else where your front tires will "droop" down before the truck bounds down on them and compresses the suspension. This will result in a pretty violent shock to the suspension. There is a way to help, not fix this. In the same way the lowered guys flip the ball joints to retain better range of motion (and they can flip the lower to get a little more drop, but this won't do anything for you in this case) you can make spacers for the upper ball joints, say 1/4-3/8" thick to gain a little more downtravel. Fabtech used to make these but discontinued them. Again they don't lift the truck any more, but do allow for a better ride.
Lastly, the tire choices. Keep in mind, by adding taller tires, you will lose mechanical advantage, which means lost power and acceleration. Also, it will make your speedometer and odometer read lower than what you are actually doing. Along with the taller tire, comes a heavier tire, which will also slow you down and hurt fuel mileage. My tires are 10.7% larger than the stock tires, so I can multiply the mileage on the trip meter by this to know how many miles I have actually traveled and get the correct fuel mileage, but even so I have lost about 3mpg going to the bigger tires.
When looking at tires keep in mind the weight of the tires. Get the lightest weight ones you can, it makes a huge difference. Most larger tire sizes will be LT or light truck sizes, these are much heavier duty, and therefore heavier than you need, try to find a P or passenger car tire in your size, these will be significantly lighter. Also the heavier tires will increase braking distance and fade, so always be aware of that.
For example, going by the kumho tires I have,
A stock size P205/75R14 Solus weighs 20.5lbs
My P205/80R16 Road Ventures weigh 34.9lbs , a huge jump attributed to the larger size tire and knobby tread
Going to a LT235/75R15 that is the same height as mine, and just a little wider, jumps to 40.9lbs, which is not to bad, since it is a low rated load range C tire
But if you go to a LT225/75R16 about the same height, a little narrower, it jumps to 42.6lbs because of the D load range.
Now then a P225/70R16 Solus is back down to 26.8lbs.
A few pounds here and there doesn't seem like much, but considering 20lbs added per corner, adds up to 80lbs, which is almost another person riding with you to add with the lost mechanical advantage.