i have read this thread a few times now, but i dont understand why you cant use a tv flyback transformer... - for the dc source, use a LM based adjustable regulator
they are actually quite stable with such a low output. very accurate flybacking,,, infact im about too built one myself for my HV motor experiement, as my current HV PSU is just too big and heavy
https://www.Utube.com/watch?v=AAqq1uNIfXg]https://www.youtube.com/watch?v=AAqq1uNIfXg
this power supply goes too about 1200v with tiny load, - or 700v with 100ma load.,, but using a MOT, making it bulletproof via the old ned kelly method.