I've got my drive circuitry nearly finished now, it's a mega-bodge on some proto-board but it does work very well.
One problem that i've come into is frequency instability, seems that even small changes in RT make massive difference in operating frequency.
Using a 2n2 CT i get 12 kHz with a 5k1 resistor, 100kHz with a 2k2 resistor and about 50kHz with a 4k7 resistor, i might put a 10 turn trimmer in place of RT to set the frequency more accurately.
So far the gate drive transformer was the fiddliest part to make, finding the right core took longer than i'm willing to admit.
In the end i settled for a core from a common mode choke from the same ATX PSU.
I made it a 1:1 transformer with the same construction as in an ATX PSU, bifilar wound secondary sandwiched between two primaries, 10 turns each.
Gate drive signals look super nice, i used the signal on one of the GDT drive transistor bases as a reference to check if my gate drives were correct.