It went well, just waiting for the prototype to come back from the manufacturer now- thanks for the help.
Getting more work from this too, which is with another client.

I got netpbm installed with some sudo terminal commands but, golly it could sure do with a GUI!
Not sure I've the time to invest in learning it's usage at this point.

Interesting how the Flexify plugin from Flaming Pear did a good projection but it didn't match perfectly with the gores posted above and the manufacturers projection didn't agree perfectly with either!
Small differences but I'm getting the feeling that there's a deal of interpretation as to the optimal approach to this task.
I added a 2cm bleed all round each gore so I'm hoping that'll absorb any errors.

While looking for a Mac version of Netppm I found http://www.avenza.com/mapublisher, which looks good, though also may be far too advanced for me.