OK so 1hr 45 mins to get this lump off. Good going considering the 4 branch exhaust is a pig to undo

And the damage - well it's not pretty but it could have been worse
The crown is marked up but no significant damage:

The bore has some minor scoring in the top 25mm:

And the head is much as the piston

The valve seats have some minor marking as does the inlet port where the washer must have bounced around for a while. The inlet valve is bent and the exhaust might be. I'll replace both.
The plan is order the parts tomorrow, clean everything up tomorrow night. Fit the bits on weds and let the cambox gaskets settle, try to shim on Thursday night and order any missing shims on Friday for final shimming and reassembly on Saturday.
We'll see how it goes.