Yeah I edited my post cos that's the main thing. 303 (and 606) were mainly aimed (somewhat unsuccessfully as you say) as backing boxes for bar musicians or for karaoke weren't they? So not really that many major recordings made using them, initially.
The thing about it being clean sort of makes me think it's real. I'd imagine that someone doing a soundtrack to a bollywood film would have better better boards than were probably avaliable in chicago/detroit etc. It sounds crisp but kind of thin/reedy which makes me think it could be real.