However they are not super cheap, and do not come with a cabinet of any form. Most don't have the EQ options that the OP was looking for either. Still, I think they are interesting...
So I've obtained a different combo with controls along the front.
This looks like a straight forward case of flipping everything upside down, except for one thing:
All the pots and sockets for the front of the amp are mounted to a perforated section of the circuit board, which is joined to the main board by a bunch of really short leads.
They designed this section to be broken off the main board, but installed close to it in a similar relative position. This would mean the valves are hard up against the rear of the front control panel, possibly coming close to (if not touching) the speaker.
To pull this off I'm going to have to use much longer connecting wires and move that front panel to the opposite side. It was inevitable I guess, but it looks like I'm going to have make use of a soldering iron after all. I've never done that before, anyone go any pointers on how to unsolder those wires and replace them without destroying the whole kit?
Also as Simon pointed out, with this amp getting installed upside down, the valves could shake loose and will require some kind of retainers. From what I can see, retainers usually screw into the base of the socket, but these sockets are soldered in place with nowhere to screw in a retainer. Is there a work around for this? Would I likely be able to just screw them into the chassis?