Tanobe sensei says when you examine a signature the last thing you should do is go to the references (you need to do it, just it is the final step and you should formulate an opinion first).
There are things I don't like about the mei because they are there, before getting to the references. There are some things I think are wrong and then some things that bug me.
I could entirely be wrong in my analysis. It's hard with this mei because the blades signed TSUDA are made at a higher skill level later in his career. This early mei, generally the work is not as good as later pieces. So there are fewer references to look at as when they are published, people like to publish the TSUDA work.
The variations in his signature have also to be understood as progression in time, they go along with his skill increasing. In the case of looking at mei from the same period they should match for their habits.
Tanobe sensei also said to make a list of pros and cons about a signature. This means that it is not always open and shut but some stuff is in the grey area and then the work is going to have to be used, or yasurime, etc. The whole blade.
My confidence level is based on how much I think this statement affects a conclusion of gimei.
Maybe pop this link open in a new window so you can look at it side by side with my text.
1. this line is curved in the middle and if you look at the work, he actually uses a straight line here. It's not a sine wave basically but it is a straight line with two curved ends on it. Like you took a pipe and bent one end of the pipe and the other end of the pipe and you left the middle straight. I could be wrong, but this is what I think here and it is a subtle difference. Confidence level 4 out of 10.
2. I don't like this at all. This is two chisel marks and I don't see any examples where there is one. The one mark is rather unconfident and the other looks like it's kind of on top. I consider this a mistake until someone shows an example that is accepted that has two strokes in this part of the character. Looking at oshigata there may be extended strokes where this is two strokes but headed in the same direction, not 90 degrees like this. Confidence level 8/10
3. I would be happier if this curved outwards. This does happen with it being straight but the examples are rare. Confidence level 1/10. Note how the stroke ends in kind of a rounded feeling. This happens I think more often than in legit examples.
4. The atari at the top was done in the wrong order. The vertical stroke punches over the horizontal stroke and it should be the other way around. This does count, it is one of the gimei "handbook" things to look for. 8/10 confidence.
5. The long horizontal stroke in this case is concave like a shallow bowl. If anything it should be curved with a gentle S or in the other direction, like a hill. The horizontal stroke below it is not so well organized. I think it should give the appearance of a single stroke whether or not it was made as a single stroke. See the example I put in. 5/10 confidence.
6. Stroke order is wrong again. This mei starts with the horizontal line on the bottom of the box, then adds the atari to it, then puts the atari on the vertical line beside that, the right side of the box, which cuts into the lower atari as a result. In the other examples there is no atari on the vertical or the lower line is pushing into the vertical, and I think the vertical was cut in first. Confidence 4/10.
7. Lower right part of the SUKE rightmost radical starts too high, should be aligned with the rest of it. As well there is a hiccup in the turn. No doubt this is a hard thing to get right, to execute the smooth seamless turn that Sukehiro makes in the other examples. This part I really do not like. The top part of this line as it goes around the bend, also is not so clean and in Sukehiro's examples it gives the impression of an unbroken line, whether or not he cut it in like that. It should look like a paintbrush did it. Confidence 6/10
Overall each one of these things can be handwaved away, in such a case, it becomes hard to know when you are forced to stop handwaving. Who decides how much handwaving is the limit. Not me. But enough handwaving and we can come to the conclusion that the Honjo Masamune has been found 10 times already in the USA, with various excuses, maybes and buts.
What we have to do, as Tanobe sensei said, is make a list of the pros and cons and weigh it out. It is certainly not slam dunk but also it is close enough to want to look more and see what the blade looks like as well as the finishing at the top of the nakago and on the mune and jiri.
If I was playing roulette on it I would bet against it, but also would not be shocked if it went in and passed because some of these discrepancies you can find on individual items if you look hard enough. I think the stroke ordering are some of the bigger problems though, as it requires seeing the bottom of the strokes and this is clear in the photo taken but not clear in oshigata. So if you were copying from oshigata you wouldn't know which stroke came first out of Sukehiro's hand. There is an order you are supposed to follow normally and then there is what the smith chose to do. The question is, did he mix them up from time to time and my instinct is the answer to that is no. Whenever you get involved in making too many excuses for something then the reason is usually inevitable.
I want to believe
It would be different if I owned it, I would be looking for reasons to hope, but all of the above would prepare me for it flunking. A lot of people are never prepared for it flunking because they only want confirmation, they don't want anyone's real opinion. So when they don't get confirmation it leads them to believe there is a problem with the judge.