I was given an old tube based high voltage power supply. It looks a bit dodgey - so I'm going to scrap it for parts. There were two nice 150V argon voltage regulation tubes in it though (OD3). There is a potted high voltage transformer module which gives a nice range of taps 425V at 100mA and also a 5V 2A tap for heaters. I will probably end up using this potted module as the basis for a bench supply (A much less scary, much more insulated one).