Is the bowl you are thinking of ordering for a Performer? I know they make the "new" copper Performer for the 2014 year. Otherwise, if its not a Performer bowl, you won't have a good way of mounting it to the frame of the cart. By the way, I think ANY colored bowl and kettle look nice in the SS cart. Here is one I made up earlier this year.
Here is what your brownie or copper might sort of look like if you make one.
Copper
Brownie