I would consider contacting an Italian attorney and have him look at the documents you received. I was contacted by a German client some time ago, who had been told he had inherited $US 8 million, and all the documents and letters from the bank and court he had received looked almost real, but for someone practicing here in the US it was obvious that it was a scam. A German attorney would not have known that. Also, if it's a real inheritance, the attorney will be able to help you collect it...
I agree with the previous poster, but would like to add that contract drafting is not that simple. There are many other things you need to consider and should include, i.e. attorneys' fees, confidentiality, termination terms, etc. I do not understand if you would like to set up a business here in the US or in the UK, but you should know that your partner could be owner of a US business, he doesn't need to be a US resident.