If there are cases of both sides, which I doubt, you have a valuable find. But you have to see them to appreciate them. At the National last year in Germany, there was one 2010 with the mirrors, other 2010's there but only one set of mirrors. I think only 7 or so Opel GT's made it to Europe, Dave can give you the exact number on them.
NorbertGT actually sat in the car and was totally amazed by the view from the car. He thought I was nuts until he actually used them.
I would assume if you have Solstice mirrors, you could just change over the base. I have a set or two of the stock Sky mirrors, I will try to remember to look at them the next time I am at the storage facility.
I guess as far as mods go, not a big deal for the Sostice, but for a car that is rebadged as an Opel GT it is the ultimate mod as far as I am concerned. Currently there are only 5 actual sets in the world, and I have 2. They did such a good job designing them, most people never notice them.