I never saw this before but on a google search it looks like someone asked on Facebook about it showing out of stock on Speedmaster's website. I don't have Facebook, but it appears that question had no response.
A place on ebay, from Austrailia, says they have more than ten available, but says they won't ship to USA.
The description implies it's a dual bolt pattern for LA and Magnum, but the one picture looks like LA only.
Interesting.
re the dual bolt pattern, the speedmaster 'rpm airgap copy' i bought had interchangeable ally bungs to get the right bolt angle. you can see the bolt holes are actually slots in the pic so i assume this uses a similar setup.