get a body lift if you must have a lift, NO HIGHER than 2" they are not the best but it is only like 100 - 120. It will save you a TON of money in the long run on front end parts. The more you crank on the torsion bars the faster you will kill the front end. Believe me I have been there and done that, wheeling a blazer or any s-series is super expensive after eating ball joints and wheel bearings every other month.
But…
If you must absolutely fuck with the suspension get 2" shackles for the rear and raise the front no more than 1" by cranking the bars. Should be about 4-6 turns each side. Then put a body lift on and you can run a whopping 31" tire.
After the above is done then you can start to enjoy the wonderful world of broken parts, like the sweet 7.5 10 bolt you most likely have and front cv’s and ball joints and wheel bearings and front diffs and cases.
best thing to do is go trade your blazer for an xj you will already be way ahead of the curve.
This is from personal experience, best of luck.