5/5 drops are ok as far as not rubbing alot becarefull of how fast you drive down a bumpy road stock lower control arms will bottom out with the spring spindle combo and with a 255/60 15 the control arm only sits 3or 4 inches off the ground
and with any drop you really want to put new urathan bushings in makes for a much better and quieter ride
I have yet to be able to try this yet a spig control are drop for the front end to get a little more clearance on my lower control arm something you may want to looki into