It wasn't right. I wasn't happy. So lets redo it!
My biggest worry about removing the cylinder wrappers was that the valve covers (?), three layers of tiny square etching, would float away if too much heat was applied.
So I carefully applied the heat only to the wrapper. And miracle of miracles, the wrapper slowly peeled away. The tiny washer on the edge of the wrapper pinged away into infinity, but that was the least of my worries.
The wrappers were cleaned up and reprofiled. I've overemphasised the curves on the basis that when butting up to the plates, the curves can be pushed out slightly; easier than trying to do the opposite and make a curve tighter whilst soldering.
Finally, the most laborious task is to clean up the face plates. I've wicked away a fair bit of excess solder and then spent time with files ensuring that there is an adequate "step" between the outer and inner plate. This is what the wrapper will sit into if I've done it right!
Was it successful? Well I'll tell you next time...