Okay the feet are not an issue any standard low shank Singer foot fits that machine so your good there. But it is far from a bootleg.
The NeedleBar has one in the PL (picture library) and its an older Admiral. What I find interesting is that it is a model 15 but the tensioner is located where the 99's are. There are a lot of little things that peak my interest about this machine. I think you have an important machine as far as the Japanese 15's go and it could possibly be a missing link my research.
If it were me I would use it and enjoy the machine and you will find that the overall quality of the machine to be better than any Singer 15 that you might use! Who knows this might be your favorite machine to use. ;-) ;-) ;-)
Billy