It isn't that those old charts are outdated as it is they don't specify the gauge of wire and wire type the numbers were based on making them essentially worthless. Had they listed the wire type and wire gauge, those charts would be 100% valid.
To know what power range a coil needs to run at, resistance alone tells you nothing. You also need to know wire type i.e. SS, Kanthal, nickel, nichrome, etc. and you need to know the wire gauge. Any chart that doesn't list those three variables is completely worthless.
From there its a simple matter of using a web calculator like
Steam Engine to plug the numbers in. There are also a couple of handy apps for smart phones that do the same thing.
On factory made, pre-built coils, you might not have that information, though most quality manufacturers list a wattage range the coil should be run at.
As far as your mod goes, so long as the wattage range and resistance of the coil fall well within the mod's specifications, you really have nothing to worry about.