Sorry for taking so long to respond to this one D-type, but my old PC (which has now finally expired for good, so I have just bought a new laptop) seemed to block me every time I tried to reply. For some reason I had the same problem with a couple of other puzzles, so hopefully I should be able to access these as well now.
Anyway, after all of that, sadly this is not a Spedeworth Mini-Stock conversion, so still open to all.