Resistors for INS1

Hello,
in the manual of the ClassicNixie v6 is a value of 270K mentioned.

I found in my workshop 220k and 300k resistors.

Is the 270k a experience value?
I found on the Internet this values:
 - Burningvoltage min. 65V, max. 90V 
 - Current 0,5 mA

With 170V, a resistor of 210K sould be enough or do i calulate with the wrong values?

I know the question is a bit boring, I was just wondering where the 270k came from
 

The INS-1 is a slightly strange creature that doesn't always give reliable results. 270k is a good median value resistor to work in most cases. A 300k will give longer life, yet may suffer from flickering. A 220k will run the tube a little harder and probably be more reliable as far as not flickering, but it may cause a shorter lifetime of the tube. Your best bet is to try all three, one at a time, on a breadboard with your INS-1 tubes to find the highest value that doesn't flicker.  I wouldn't use lower than a 200k unless you like changing tubes frequently.

Thank...now i ordered 270k and everything is fine