if i understand your question, you are asking if you should submit the sword to the SF shinsa... Yukimitsu is clearly a "big" name so going carefully is wise. As the blade is signed you could submit it. I have not seen it to judge condition, but the shinsa team should be able to give an opinion on the mei. If they think it is genuine, but can not see enough of the work, they will tell you that. If they say it is gimei you may be able to ask they why if you are at the shinsa (or they may note the reason). Then you can go from there, i am not saying one NO means it is bad, if you feel it is genuine you can go further. But having the shinsa team here is an advantage and with so much upside (if you really think it is good) there is no reason not to submit it.