I bought a 1998 4WD F150 with a 5 inch suspension lift, To achieve to the lift in the rear a 4 inch steel block was placed on top of the already 2 inch factory block......I would like to replace the 4 inch block and the factory leafspring with one 6 inch lift spring and I plan on turning up the torsion bars to gain 2 more inchs of lift. Is this possible? and what are some good brand/companies that manufactures these springs?