I couldn't find my old post for some reason so I decided to make a new one
I fitted the inner ring to the pier head lastnight, welded it in three places so it wont come off. Decided not to weld the whole way around incase of flexure. The ring has been machined to fit perfectly into the pier base which I am in the process of doing now.
There is still a bit of cleaning up to do on the pier head, mainly cosmetic, ready for it to be powdercoated to prevent it rusting. The whole pier head weighs in at 19kg.