I'm planning on lifting my '87 Suburban 6" and running 35-36" tires. I'll use 6" springs in the front, I'm considering using ORD's 4" shackles in the back and I need about 3" more lift in the back to level the truck. Do I need to use new leaf springs in back? I hear it's a no-no to use blocks, but I get less spring arch with blocks and my stock springs, plus all the new 4x4 trucks have blocks from the factory. Are blocks really that bad???