Today, finally, fitted the pier and leveled the adapter plate.
Relatively straight forwards, despite the pier base being slightly out of true. But the bolt positioning was perfect.
Installed the NEQ6 and C9.25.
It will be a while before I can do a proper polar align due to an inconvenient tree obscuring Polaris in the summer. However the centre of the pier is very close to the centre of the tripod previously (within 0.25") and I kept the Parked settings of the mount. Having also used a laser guide to mark the wall in direct line of the mount peg, alignment should be close enough for observing and short exposure imaging.
Assuming it ever stops raining that is!
Now focusing on running the many USB, power, and dew heater leads, fitting the dew heater and USB hub, and trying to reduce the overall spaghetti look!