Thanks everyone for your help and the great info you gave me!
I'll definetely follow your advices and check the italian forums you pointed me to and maybe have a chat with Massimo.
I wanted to know an approximate value of the tanto only to see if it was worth restoring it.
I really like the tanto even in this "beaten up" look, it makes me think of all the people that have used it, passing it along the generations, and i wouldn't mind keeping it like this.
But a quotation for a polishing job, maybe with a new shirasaya and habaki wouldn't harm anyone, so I will ask around!
Thanks again!