New Primary Design

Hi All,
         My next coil has just grown from 2.4kVA 8"dia. to 4.8kVA 13"dia.  
Unfortunately I now do not have room for the primary that such a large coil ( 
147cm high 32.5cm diameter) would need using the normal design ruled for 
small coils.  Darn.  I wondered if any of you with experience in coils of 
this size, Dr. Rez etc., would be able to give me any advice on the smallest 
primary I can get away with, as the rule of secondary length = primary radius 
does not seem to be so rigorously used on big coils as on little ones.  The 
wire is 0.6mm diameter copper magnet wire.
Also just a note to everyone who came forward with caps for sale and/or 
advice, thanks guys.  I now have an 8F 10kV cap on its way to me.
BTW:Thanks to Bob Golding for the xfmr core, boy is that one big limiting 

Sooo this is your second coil............
Nick Field