Wimberly Mounting plate and Mamiya 500mm f/4.5 APO

Hello, I just received a Mamiya 500mm f/4.5 APO that I picked up on eBay from Japan. It is great and expect a review and comparisons to the 300mm f/2.8 APO soon. They will both be coming with me to Costa Rica in a few weeks to hopefully make some cool images.

But, before even worrying about Costa Rica, I have to figure out how to mount it on my damn Wimberely Gimbal Head. Of course I know how to put the lens with an adapter plate on the head, because I have done it using the P-10 plate on my Wimberely and it worked perfectly from installation to in testing.

I purchased the P-50 and the P-40 plates since they were recommended to me for the 500mm f/4.5 APO lens However, I cannot figure out anyway to mount the plate on the lens where it will not rotate. Surprisingly the P-10 works best but it still rotates. Even using the extra small screws doesn't help. Any help would be greatly appreciated.

Attached are pictures of the bottom and side of the lens collar.