Hi Athanasios,
Welcome to the forum.
Unfortunately, (and I don't mean to be dismissive, so please don't take offence) you might already know as much about the blade as you are going to. The problem with shinshinto, and to some extent shinto, blades is that they often lack any distinguishing characteristics that can help to place them geographically or within a particular school so it is going to be difficult to tell you much more about an unsigned blade from this timeframe than you already know. If it helps, there's nothing there that suggests that it is anything other than as described so you at least have the genuine article.
Did it come with any kind of scabbard or other fittings? The habaki looks like it is better quality than normal so that is encouraging as someone thought enough about it to give it more than a basic outfit and I find the overall shape quite graceful and easy on the eye which is not the case with all blades from this period so I think that those are positive points.
What might help when you have a moment is if you are able to take some photographs of the blade as scanned images tend to obscure details. If you are able to do that in a darkened room with a single point of light, place the blade on something soft and on a flat surface and you will be able to move the blade around in the light to reveal the details that are there. If you are able to post some pictures of the detail in the hamon, hada and boshi you may get some better comments.
Apologies for not being more helpful and, once again, welcome to NMB and this fascinating hobby and congratulations on your new blade.