It doesn't work with the 645 Super, 645 Pro or 645 Pro Tl unless the length of the "plunger" on the grip is modified - the location is right but the spacing is not.
Based on your photo, the grip that you have listed for sale is the C330/RB67 grip and is actually a different grip than the Deluxe L grip listed in the manual. The cold shoe wasn't an accessory for the one you have listed, it is included with that version of C330/RB67 grip.
It's interesting that your grip works with a 1000s - I never had the opportunity to try it on that camera.
I used to have one of the Pistol Grips that are of the same vintage and are listed along with the Deluxe L grip in that manual. It came with a batch of Mamiya stuff I bought off of eBay. It didn't work with either my C330, my 645 Super or my 645 Pro, all because of the position of the lever that is supposed to engage the shutter release.