Ryan,
First, measure the pilot of the reamer you have. The people involved with this wildcat ground their own reamers and it is possible that the pilot will already work with a .284" barrel. If not, you can pretty easily grind the pilot to fit (the neck, not so easy). By changing the expander button to hold the smaller bullet, and neck sizing to keep the case centered in the chamber you may be able to use a .284" barrel satisfactorily.

Mike