personally I would build up under the frame with heavy wall tubing and keep the axles in direct contact with the springs without the blocks
Ed So.Calif 1950 Ford F1 street rod 1968 Baha Bug with 2.2 ecotec motor 170 hp, kingcoil 2000 National Sea Breeze 5th wheel trailer 1998.5 Dodge 2500 4x4 Cummins,4.10 gears,turbo,trans,injectors,oil cooler,lockers,edge EZ, 35" BFG's, air dog lift pump etc.