[Arran]

It does seem to have an interesting mix of octal and older based tubes, like it uses a 25Z5 rather then a 25Z6 but uses a 26L6 instead of a #43, it also uses a 6D6 rather then a 6K7 but uses a 6Q7 and a 6A8. The ballast number won't tell you much, it's basically a standard pre war AC/DC design with five 300 ma tubes, the only thing that may differ is the pilot bulb tap/s on that ballast. While not exactly an AA5 it should be possible to use a schematic from another radio with a similar tube lineup for servicing if a model number can't be found.
I would think that if one could go through either the Rider books or Beitmans you could find out which set it is by comparing the other components to the schematics. It is a weird or uncommon model though, I could not find a photo of a Fada with a cabinet of that exact design, most seem to have the grille bars arranged in a "T" pattern.
Regards
Arran