Replacement for a Corcom F2987A EMI Filter

I have two failed Corcom filters in two DEC Rainbows. I see some spares available in the US, but shipping to the UK is likely to be prohibitive and I would like if possible to find a modern equivalent. It is this one: http://meci.com/corcom-12-20129-01-emi-line-filter-model-f2987a.html. I am told it isn't enough to know the current rating (2A at 240V) and that it you need to know the source impedance (and the impedance of the load?). Does anyone know the spec for this filter so that I can get a suitable one? Incidentally, when I fix these PSUs, I may be wanting to pass on one of the Rainbows. In this case it would not be free because I had to pay for it (and drive a fair distance to get it too). The one I may pass on is in a vertical pedestal. I may also have a third one to pass on which has a fault on the system board, I don't have a logic analyser capable of helping me to find the fault though. Thanks Rob