Loading is entirely for the benefit of the preamp not the cartridge. Here's how it works:
The cartridge is an inductor. The tone arm cable has a capacitance. Since they are in parallel, the result is a tuned resonant circuit, often active at +100KHz frequencies or even into the MHz range.
If your preamp isn't happy with radio frequency energy coming in (and that is what I'm talking about) then the loading is used to detune the resonance and thus kill the RFI (Radio Frequency Interference).
It is therefore non-critical- a low enough resistance value is all that's needed if your preamp can't handle RFI (and if it has a switch for loading on the front panel then that is the case).
I would try it without any loading and see how it sounds though! The load causes the cartridge to do more work and thus makes the cantilever more stiff and less able to trace higher frequencies.