I've also got a Stella, and for all the hours I've spent scouring the internet for information about it, I've come up with very little! There's just not much information out there about this brand... in fact, I've never even encountered a complete list of the models Stella offered. The SX-6 was Stella's entry-level bicycle... but it doesn't look to me like you've got one of those, as your components and paint are too nice. On the other hand, all the upper-level Stellas I've seen have had more ornate, long-point lugs, which you don't have...

I think bobbycorno's got it right... I'd say you've got Stella's equivalent to the Motobecane Grand Touring.