Replace the bodymounts at the same time, I went ahead and put in the poly mounts. Cant speak for the K5's from experience, but I believe you have to drop the gas tank. I put a 2" on my truck, hadta lengthen the transmission shifter rod, but the kit came with the piece to do it. Performance Accessories plastic pucks & ORD's aluminum pucks(only come in 1"), are the only 2 Ive seen.
160 seems kinda high, I think I paid ~100 for mine, but it is a truck, dont know how different the kits are.
Also, if you have a 2 piece fan shroud you will have to space the bottom half down, or if its a 1 piece, you will have to cut the bottom of the shroud off.