[Arran]

I think you could solve the current issue with filter chokes by using two in parallel, but I'm pretty sure that you would need two identical ones that are each double the DC resistance you need, that is unless the 675 ohms is measuring reactance and not DC resistance Or you could just pick the one that's closest in current rating, but is at least in the ballpark for DC resistance. It's the inductance in Henries that is important, but it's very seldom that the service data would tell you what that is. You could also try making a solid state filter choke, as documented in a back issue of the AWA Old Timer's Bulletin. I just hope that the 8000 ohm section of the field coil wasn't used for filtering the B- leg of the power supply, or something like that, where you can omit it without consequence.
Given the technical specs on these speaker I can't figure out why the audiophools in Asia or elsewhere would want to play with them, they seem like a PITA to use outside of a McMurdo.
Regards
Arran