Hello David,
Thank you for posting the pictures. I have no laptop at the moment so I can not get hold of my pictures.
I was on my last test ride before the MOT when I ruined my engine.
I got the noise down from 110 db with a Gold star silencer to 86 db with my self made silencer. Measured at 4000 rpm static. That is how the test goes in Germany depending on the standard rpm for the original bike.
When the engine is under load its a different story though.
But I think we are digressing .
I wish Harry all the best with his Vincent.
From my personal experience I would completely disassemble the engine and check everything. An easily solvable problem can bust your bank account if you break the engine.
Also with not so many specialists left, it could take years to get the engine back.