A chance listing on ebay has given me a big clue to this mount:
2004 Southern Cross Sirius reflector on Ebay
The photos of this scope shows the exact same mount I have. The clue being an old scope retailer called "Southern Cross Telescopes".
I picked up an old 8" f/4 set of optics from an old Southern Cross scope last year. I suspect that it could be a rebranded GSO from a few years ago.
I did a search on Southern Cross 'Scopes and came across this old IIS thread started by Lars also asking about the providence of this same mount. Here Lars actually has spotted a similarity to the Takahashi EM-10 mount, even the EM-11 - the body castings/moldings are identical:
Tak EM-10 Clone mount?
So, I guess I should re-fire Lars original question too on this: does anyone recall Southern Cross Telescopes? Was Southern Cross Telescopes an earlier version of today's Sirius Optics? Anyone have some idea on this mount?