The Zhi frame is 135 as is your hub you should have no problem getting snail cams into the frame, if you have to pull the rear end of the frame slightly apart to get the wheel in then I would recomend you try this before any of your other options, also what gear ratio are you using on the pro 2 hub? The new frame is designed for 18:15 NOT 18:16 as said on other reply's to this topic....
Hard to explain but as the drop-out is designed to save weight. where the bolt is placed it has to only screw half way into the frame as you would hit the CNC flange zhi have made to increase weld area/save weight on the drop out, also due to this flange you could not run outer cam's.