It seems pretty obvious to me ( after a bunch of Googling ) that your Interface 200's were simply export versions of the EV Interface B ( but made in Switzerland with an added LPad for the tweeter > no doubt ).
It's also obvious that the Interface 100 is the export version of the Interface A ( or Alpha ).
I would simply use the same parts ( as found in the "B" or Beta > maybe even the 100 ) for your refurbishment ( if you can track them down ).
BTW, E.V. is now owned by Bosch ( a German company ) .