Chansen,
these mountings have been put together very recently. The SAMEGAWA was "repaired" with 2-component glue, and the MENUKI have been glued on the TSUKA the same way - amateur work! TSUKA-ITO is missing, so, no, this KOSHIRAE is not 'period-correct', which by the way would not be a problem in terms of quality. Mountings were often changed in the life of a blade.
To me, the blade has a later MINO touch; the HAMON reminds me of SANBON SUGI.
As mentioned before, you do not know what you have there, so it is much better to save your money for a moment and look for a better sword. Here on the NMB, we have reliable dealers and good offers for your money.