[SWEET7T]

Nope...
more arch means that the spring is farther from the frame, which means that your axle will be lower, causing your truck to ride higher.
If you do a spring-under on your truck with the current springs, you will lower your truck by how thick the spring pack is. If you get new springs of the same type (OE replacement springs) They will be somewhat taller until the settle (keep in mind that your current springs may also be sagging causing the truck to ride a little lower than it did when it was new).
So, if you did a spring-under conversion and still wanted to go even lower, you could add a little block between your spring pack and your axle.