Big TC design

What I am wrestling with now is a rough design of secondary and primary

- secondary 15" wide by 60" high, 931 turns, 73 mH, 112/62 kHz
- toroid 10" section 60" outside diameter 62 pF
- primary spiral 18" inner diameter, 12 turns, 128 uH
- --> Primary capacitor must be 0.056 uF

I would like to maximize the capacitor size, to be able to pump more energy
into the primary. The problem is that, having a big secondary, I must have
a big primary inner diameter too. With just 12 turn of primary my capacitor
(required to be tuned) drops down to 0.056 uF. I would have liked at least
a 0.1 uF...One possibility is to use only 8 turns (--> Cap = 0.123 uF).

With 0.056 uF and 20 kV the cap energy would go up to 11.3 Joules, while
with 0.123 uF up to 24.6 Joules.

Any suggestions anybody?