As for parts bin,
I've got SunTour Hero or SunTour ARX that could go on there. ARX comes with a top-of-the-downtube shifter mount, which I'm not sure will work with this frame. I haven't checked the status of my bar-end shifters.
I don't know much about Suntour, but I heard ARX was supposed to be a competitor to 105 but just wasn't as good.