You can do any of the following:
1. Buy a GDI Radiator with the filler neck and rework the heater hoses with a late model heater valve.
2. Buy a moroso aluminum tank to replace the plastic. The moroso tank utilizes a standard radiator cap.
3. Insert a moroso inline radiator cap in your upper radiator hose and eliminate the bottle. you prob. should add a standard overflow bottle if you do this. Go to Jeepinjoe.com for the lowdown on this option.