I did one, but had to change your model. I recut the top out of the base using an actual "Arc". I dont think you can rotate a non-arc on a non-arc without binding, but I may be wrong. Maybe an engineer can chime in here.

In this model (if you have MoI V2) You can take the rotation widget of the top portion and place it at the center of the arc i used to cut the new face with, and rotate the face out of the base nicely. With this method, you could probably redo your phone to look like you want and do the slide properly. Just make the cut with a true arc and it works.



[EDIT] If I used too much curve for the cut, just make the arc bigger and redo it to get a flatter top portion. [EDIT]