to keep from bottoming out your going to need stiffer than stock springs.

as for how much drop, use a ruler to measure the distance between the of the fender and the top of the wheel, that's how much drop in the spring your going to need. you probably will not find something exact but just find something close enough that you'll be happy with

check ebay for the springs or pick a shop in the shop's section and ask if they carry the springs and for a price on tem