The drop spindles will work fine, but you should get 17 inch rims to give you enough clearance so that in case of a flat, so you do not rip your lower suspension arm off. The shock end will hit the ground before the rim does with 15 inch rims. You will also have to get new ABS sensors for the new spindles.
The springs are safer, but you run into the issue of camber and suspension travel. The camber can be fixed by removing .030 inches of shims for each 1/2 inch drop (.120 inches for a 2 inch drop). Suspension travel can be partially restored by cutting off the tapered part of the stop on the lower arm.
Special note for you...No one makes 17 inch full moon hubcaps that just snap into place. only Moon makes smooth hubcaps for 17 inch wheels, and you have 2 mounting alternatives. 1. screw them to the rim at 3 spots, with 10-32 screws, which makes it a pain to check your air pressure, 2. dzus fasteners...makes checking air pressure easy, but you have to weld mounts to your wheels (Moon rents the template). The Moon hubcaps are aluminum, and cost about $55 each for just the hubcap.
There are a number of places you can get the parts, just do a search on ISSF, and also check ebay, bing, and google.