Yes you would keep the Fox coilovers with the lift. The overall height that you end up with is going to depend on what you have the coilovers set at. If you set them down to stock height you can be as low as 4.875" of lift (which is what the Zone strut spacer will give you). If you have them up to 2" then you'll obviously be at 6.875" of lift.
Depending on where you want the front end to be at you will either want the 3" or 5" rear coils to get the truck sitting how you want. If you want it lower and level, then the 3" coils will be the right option for you. If you want it higher then go with the 5" rear coils.
Shoot an email to
[email protected] and let them know I sent you. They'll get you a good quote for either kit option that you're looking at.