TaylorVA and I had a great conversation this evening. I took my topper off and sent him some photos. We thought these may help others.
Note: I really did try to keep the original Dalek head as possible, but a lot of material was needed to be removed to get it to fit over the mech. I also mounted the mech backwards from the instructions, but it still works great.
I also trimmed off the flange off the top of the Dalek Base. This allowed for a nice tight gap between the Dalek top and the Dalek base.
Enjoy,
faz