Done some testing and was very pleased with the results. The coils in series are 600 turns each in total give 54mH inductance and 63 Ohms resistance and running the EHT at 3.5 kV it needs approx 95mA for 50mm deflection. So for a first go I a pleased with that.
https://youtu.be/5KjOY8nr0j4://
Cheers
Adrian