Front: SW20* rear shock inserts then you can either space the shock, or do the right thing and cut and shorten the strut casing. Then slide on some adjustable platforms and run any spring rate you desire. Camber plates, RCA's, done...
Rear: Any 5.5 ID spring will work in the rear, EA/EF front Falcon springs work and are easy to find but there are plenty others. Tons of information online.. MA61 Lows are effectively superlows in a X7. Shocks there are endless options, if your going the cheap route then use VP/VN commodore rear shocks if you can find a wagon thats even better cause its stiffer. Otherwise Isuzu trooper/jimmy, Ford focus, E36 bmw shocks work. You can modify any shock too suit really.
Or do what the others said and just splash out and get the BC gold kit. Less mucking around and you will be able to get a cert if your at a reasonable height.