Neither of those two options will work, since the on the aftermarket Brembo radial masters the bolts don't line up exactly
Oddly, I mentioned my dilemma to the parts guys at Scuderia (local shop), and he says Brembo is now making mirror mounts as an accessory.
Available as of last week from yoyodyne, they just haven't been posted on the website yet
Still, good sources for folks with the stock masters...