You will need to match this exactly, no if's or maybe's! If it passes too much or too little voltage, you could easily burn out another part of the circuit or even the tube.
Your best bet would be to spend a few minutes at a tv repair shop. You might even offer to pay for their time. just tell them what you are doing, and that you are in to amateur electronics.
Next, take a look at this:
http://www.tpub.com/neets/book7/24k.htm
Be careful!