I added up the tube filament voltages, used 125 for the AC line voltage and came up with 8.2 uF rather than 10 uF.
Ideally, you would use a capacitor rated for continuous AC current like a motor run cap, but I've had good luck with basic polyester film caps like these from Panasonic.
http://www.alliedelec.com/panasonic-...25kf/70260082/