The GS mirror perches have quite a long 8mm clear hole, so it would probably be possible to drill and tap the top half to take what looks like the 10m threaded stalk on the Wunderlich mirror, and still have the ability to refit the stock mirror.
Unless they have a LH thread on the mirror like some Yamahas, in which case you will need a LH tap.
And that would probably be a problem if you had to make up adaptors too.But this is not likley on a non handed mirror.
Actually, reading the discription and looking closly at all the photograpghs it looks like they include an crescent shaped adaptor which bolts down through the old mirror mounting hole and places the mirror stalk a bit further forward /outwards. The GS stalk hole is already on the outside of the perch, so it wont look like the photographs but it would probablY work OK.
