You could technically use this kit, though you'd absolutely need to set the Fox coilovers at a 0" ride height so that you're not pushing your UCA, LCA, and CV angles past the breaking point. Secondly, I can't really guarantee what kind of ride quality you'll get, as the Fox coilovers aren't really designed to be used with spacers, though it will probably still be far superior to stock. I know it seems like you're throwing money away, but you'd be better off ditching the spacers and trying to sell them privately. If you need 2.5" of ride height and still want a smooth ride, check out F150Lifts BOSS Coilovers