Help w/ Chokes

I'm in the process of constructing a 3.6kw power supply for low power 
testing and tuning. The step-up transformers are 4500V -at- .4A plate 
transformers from electrostatic copiers and I'm running the secondaries 
in series for 9kV. This arrangement will power a 12.75 dia. secondary 
coil tuned to ~100kHz. I know there has been a lot of discussion 
regarding choke coils and I'm wondering if someone could guide me in 
building a pair of appropriate chokes. I have limited space for the 
chokes. If I use air core chokes, I can only accommodate a 2 dia. x 8 
coil form.

P.S. What's better for Tesla service 10kV-at-.3A or 9kV-at-.4?

...Jeff (www.ddlabs-dot-com)