I haven't got to the stage of installing yet. I can't get the Mavericks Restore package to write the Mavericks dmg to my USB chips.
Everything worked fine writing High Sierra to USB chip, but the installation onto disk failed time after time, and I had nothing to bring to the forum, so I decided to lower my sights and go for Mavericks. I have downloaded the Mavericks dmg and the Mavericks Restore package, placed them in the same directory, reformated my USB chip (I've tried two, one 8 GB the other 16 GB and the one I got a working HS install on), run Mavericks Restore, it goes through the motions, reports Done, and then when I check the USB chip I find that a) the partition is unmounted although it was mounted at the start and 'b) there is nothing on the USB chip. I must have run Mavericks restore about six or seven times, on the two chips, with different configurations, GUID, MBR and Apple whatever-it-is without any change. I've downloaded Mavericks Restore a second time with no other result. I'm a bit surprised how small it is - only about 7 kb, and I can't find anything resembling code in there.
So what's to try now?