I've tried with a couple of 12 inch, 8 watt tubes, and have difficulty getting them to fire properly. With another circuit, more complex, pwm drive like the 555 circuit that has been discussed on here, same problem. Tried it with 2 of them, same result. Tried another, bigger transformer, same. These tubes were manufactured by Crompton.

If I could, I'd get one or two of the salvage tubes & try them first.