i was also looking into doing it on my truck. like you said you can buy a "flip kit" which just changes where your axle is, insted of being under the leaf it get moved over top of the leaf lowering your trucks rearend about 4-5 inches.
http://www.summitracing.com/parts/DJM-FK1024-5/
http://www.summitracing.com/parts/DJ...25-6/?rtype=10