Finally got it.

Used a UV lamp to inspect the frame and decals showed up just nice. Turns out it's a Rog Sprint frame.
Rog was an old ex-Yugoslavian (now Slovenian factory) that even had it's own team.
It's production range was from crappy city bikes (Pony) to all kinds of racing bikes. Since there's virtually no data on the internet, I have no idea where to put my aquisition, quality wise.

But, I'm sure it'll make a nice beater