help with an obscure smith please

[Mark]

I have a katana, the mei is hard to read but my guess is Bizen Kuni Osafune Ju Shigemasa tsukuru...... I find that this maker is somewhat obscure, seems to be a student of Shigesane and of the Motoshige school circa 1360's, but i can't find a reference oshigata anywhere, would anyone have an oshigata for this smith?

 

Thanks!