Its a bit of a minefield.
Same problem fitting a Juicy7 to a Pace XCM130.
Mount bought off CRC, as a 185mm PM to PM.
Ended up using a stack of washers because just couldnt get the thing to line up…
IMAG0493 by pten2106, on Flickr
Mate gave me a different 185mm PM to PM Avid mount he had spare…
IMAG1080 by pten2106, on Flickr
Notice how the correct one is just slightly thicker top & bottom.
I think the first one is actually a 180mm or something. Looks about 2.5mm slimmer.
This one in case your intrested…
IMAG1082 by pten2106, on Flickr
I bought the Superstar no7 mount, but didnt get the chance to try it. Its an ugly looking thing too.