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Block on the rear will LIFT a factory Suburban. Factory setup is SOA.The big question is How much you want it lowered?Options for the rear is shackles and hangers or a flip kit.Options for the front is drop springs (or cutting 1/2 coil off) OR convert it to 1/2T setup and use 1/2T HD spindles.SBC springs will hold a 454 ( I used them for 10 years), there is no difference in aftermarket springs concerning BBC vs SBC for drop springs. Using SBC springs will drop it about 1".