obviously there are different types and shapes around and your problem was that they got mixed up in a negative way.
So, (1) you will certainly not repeat what was so obviously wrong - and, no, I don’t believe that it was you who messed up the job.
And (2) you might try to get things straight on the second attempt. Go to square one with original parts.
Following the SI parts manual you should have viscous coupling RTC1002, if your car is equipped with air condition, and viscous coupling C.28018, if it isn’t.
Interestingly, a major supplier lists the same replacement part for both …
Now, as for the shaft all engines seem to have used C.23417/1
Said supplier lists a replacement part and states that “This bearing is now manufactured with a longer centre shaft than original which spreads the bearing load and increases the life span of the bearing. 5/8” diamter shaft with a full length of 4.875"." BTW, it looks pretty much like the lower one in your first picture.
Finally, the water pump is supposed to be C.28820. It is sold reconditioned, but I’m afraid they wouldn’t take in your Burgess pump … All in all probably around 500 EUR, but still better than having such a beautiful car and not being able to drive it.
75 XJ6L 4.2 auto (UK spec)