A bit more info on this Museum blog
(same photos, though. still none in a cleaner state)
DAEO INVICTO MY C CAS FLA
wouldn't really go with 'to the glory of...'; nor necessarily 'invincible', though this is the usual translation... is 'unconquered' the same as 'unconquerable'?
MY is a fairly extreme abbreviation, given there's clearly no lack of space, but the second inscription is equally terse
SOL C CAS FLA >
That should be C(aius) Cas(sius) Fla(vus), not Fla(vius) which would be the nomen. Sadly the nomenclature is rather undistinctive. I wish them luck in tracing other postings.
The association of Sol and Mithras is much attested, most relevantly perhaps on the dedications at the Temple of Mithras at Housesteads (RIB 1599, 1600)
