Nixies are gas discharge devices - when not conducting they are basically open circuit, and to conduct a minimum strike voltage is required across the electrodes. When conducting they need at least a minimum voltage to keep the discharge going.
The upshot is that driver circuit never gets to see the full supply voltage, so it is possible to drive with parts rated less than the supply as the off-state leakage current of the driver is plenty to keeps the nixie cathodes at a low enough voltage. The on-state voltage of the driver will be low if the drivers are low-impedance - again no problem.
The only problem is the switching transients as the nixies are conducting and the driver is not fully on - the difference of the supply and minimum nixie-on voltage will be present briefly across the driver - if this is too high the driver will be damaged. So if the supply is 180V and the min on-voltage is 80V, the driver needs to handle 180-80 = 100V...
So if you have datasheets for both tubes and drivers you should be able to work out if its a safe combination - the supply voltage can be lower than the nominal nixie voltage so long as its above the strike voltage - the tubes will be dimmer.
Also I seem to recall that you are supposed to use load-resistors to drive nixies, and these can drop some of the voltage and help protect the drivers.