you'll need a new seatpost to handle a bananna seat and the right size sissy bar for your frame, but you should be ok otherwise.
Just check the diameter on your existing handlebars, chances are you can get new bars of the same diameter and not need to change the headset. and the brakes and shifter should fit fine, but you may have to contend with cable length issues if you switch to big apes.
man apes would be cool as hell. I've been thinking about doing exactly what you're talking about to my trashed MTB. Nanner seat and some big ape hangers...could be really unique
Get some cool fenders too and be sure to keep us updated