Hello! And welcome to the forum. Ok, so here's the deal, blocks on the rear springs are kinda a bad idea. Cherokees already have axle wrap issues in the rear, and blocks just compound the problem and make it 10 times worse. So... either buy a new set of springs or get a good used set... or a longer shackle and some of HD Off Road Engineering shackle relocation brackets. Those will net you a few inches of lift without any adverse axle wrap issues. As for the front... if you gotta buy springs to go bigger, might as well get the size you want and ditch the block altogether. Most of the time you can get any size lift spring for roughly the same price, so bigger springs don't cost much more. If you want 6" of lift, you will NEED either long arms or drop brackets for short arms. Ask either shaggybob or melkorsxj, they both have run that much lift with no drop brackets and short arms, and they both will tell you that its nowhere near the ideal situation. Axle movement, poor ride quality, and handling quirks are all issues that will come up with trying to run the short arms in the factory location. Personally, I would just go long arm from the get go because in the end its the best solution, but if you do go short arm, be sure to get a set of drop brackets. For the cost, I wouldn't bother making a set (and this is what I do for a living everyday), so just buy a set.