Understood - and thank you for helping correction of a mistake of my own making.Hi, see attached!
Disclaimer for posterity, I don't intend to keep this updated, so if I make changes to the script in the future the attached version will be out of date. The "right" way to get it would be to manually copy the relevant portion out of https://mavericksforever.com/get.sh
I have good news: That worked !!
ie - found the USB stick and made it a bootable Mavericks install USB stick. (No Disk Utility required.)
Same computer: iMac 10,1
..only difference I am aware of:
Last time - running Snow Leopard
this time - running Mavericks.
..and different stick.
I expect its unlikely there'd be someone going from 10.6 to 10.9 again, so hopefully this problem wont re-occur.
Thank you lots Wow - for your time and patience !!
..and the extra learning I gained along the way.