I'm not sure what you mean by move. My end stops are just under the end cap of the cv and I still have the end cap on the CV. It all fits in tight. I could put the end stop on the end of the cv and it has enough space between the outer edge of the cv and the end stop to just fit the stock cv end cap in there. Does that make sense?
The axels do move a bit from side to side. That is how it pops out. can you grab the axel and shove it inboard and feel the guts of the cv comming out of the out board side? The end stop should stop this.
I've been messing with this set up for about 12 or 13 years. I've been thru this. You can fix it by having longer shafts made, shortening the control arms or increasing the thickness of the end stops. Flipping the cages will help a bit also.
Increaseing the thickness of the end stops is pretty easy. You can weld something in the center of the end stop ( large nut, bar stock, and end cut off an old half shaft) I'd add at least a half an inch to each end stop.
When you pull the axel apart, post a pic of your end stops. I want to see what Ross sent and how it fits in the CV housing.