[Radioroslyn]

Don't think it would a problem. The important factors are the impedance of the primary of the output transformer (not the dc resistance, that tells you nothing other than the transformer is usable or defective). The field coil resistance isn't particularly critical as most Philco set the coil isn't used to develop - bias by being connected to the ct of the power transformer. When it's connected to the + side of the power supply a different resistance will make a minor difference in the level of HV but it's usually of little consequence. The final factor is the current rating of the field coil. Not enough them you run the risk that the coil overheat and burn out. Too much and I think it would lower the efficiency as the electromagnet wouldn't make as much magnetizum.

GL