I found an interesting project of current fed Tesla resonator at http://www.sentex.ca/~mec1995/circ/hv/ss-tesla/ss-tesla2.html
and I was looking to compare the original core to the ones I have available on my shelf (ETD59/3C90, ETD59/N97). I built a few very large spark gap based Tesla and Oudin coil but this concept is quite new to me so I would like to play a bit with it.
So far, judging by the original datasheet PC40 seems like a more or less improved PC30 ferrite and the core size in the original project is quite close to ETD54 so ETD59/3C90 that I have available should be able to perform OK. I plan to make complete new electronics since I would like to add overcurrent protection and also it has to work on 230V AC.
It shouldn't be much of a problem for electronics to handle larger cores and higher power at the 110 kHz but very little data is available on this type of current fed resonators so I can just guess how much power can the resonator coil handle in its original form which I plan to use initially.