As said...brine equals ham. The butt will take the brine, but takes several days to cure. That is the problem...curing...the end product will be ham from a different cut. As was hit on the money, an injection with a natural pork flavor enhancer as apple juice or a maple simple syrup including some savory spice profiles and acidity is all you need. Make your injection concoction, inject, rub and cook. As far as what spices to use..start off with the essential basics,..salt, fine ground pepper or cayenne, garlic and onion powder. Experiment from there. I always encourage experimentation. Just go small amounts on new ingredients, that way nothing is over powered and even mistakes still are tasty, if not what you we're aiming for. Also when using spices in an injection, use a coffee grinder to grind to a super fine powder so as not to clog the needle. A last note, if you can, heat your concoction to release essential oils and then refrigerate overnight to allow the flavors to marry.
