IMO, 5in, on 35in tires, with stock axles, drivetrain and prolly engine is enough.
Any bigger and you're asking for trouble.



Besides, thats what 3/4 tons are for anyway....not 1/2 tons......

 

that high, and youre lookin at rockwell axles, steeper gearing, a bullet proof trans, a beefed up motor, plus tires, wheels, and lift... i hope you realize that youre looking at around $10,000 to get there. and thats the very least you need to do in order to handle that big of lift and tires... the D44s and corporate 9.25s cant handle much more than 35s, any bigger, and youre flushin money down the toilet. so dont even think about puttin 44s on a D44 or 9.25

 

At the least you will need to swap to 2500 running gear, then you will need a custom shop to build the suspension lift for you would probrably be best off going with leaf springs front and rear to get the height.

It would be smart to put a body lift on the truck so you dont have to put as big as a suspension lift, if you want to be redneck you could find a 2500 that has been rolled and get the frame and suspension from it and weld it to your frame.....

 

lol i mine as well just buy a 79 ford highboy. and drop a built 460 in it..

 

There's a couple guys on here that have trucks similar to what you want, and they've all had to upgrade to bigger axles.
It's not that you can't do it, but with the combination you have now, you've pretty much maxed out what a 1500's suspension and drivetrain can handle and be reliable. If you have a light foot, a beefed tranny and 4:56 gears already, you might get away with a body lift and 37's. But don't expect your front axle bearings and axles to like it.
I would suggest checking out other sites that have guys that off road regularly on them. Check out what they've done and go from there.