Not common Y-DNA

I always thought my grandfather was the son of an English immigrant who came to the US in the 1850s, but my Ancestry.com results show that he was probably Italian. I got the J-PF7263 results from Nat Geo (Helix). I am taking the familytreedna Big Y-500 to see if this is the final SNP or if I can go further. I took the 37 marker Y test with familytreedna and it came out M267 which is upstream of PF7263. I matched with only one person at a genetic distance of zero. His last name was Klemm and he lives in Australia. I then checked my cousin matches in Ancestry.com for the last name Klemm and got one hit. It was the Klemm family in Australia. They emigrated from Germany to Australia in the mid 1800s. PF7263 is associated with a Jewish group in France around 800 AD. They spread to Germany and Spain. My current theory (of which I have had many) is that a Klemm about five or six generations ago married an Italian who's descendant came to the US in the early 1900s. That's the only way can account for the PF7263 SNP, 3% Jewish, and 20% Italian ancestry. The other 6 matches on familytreedna who are genetic distance of 1 are all Jewish. This Jewish ancestry was not known to anyone in my family.

Hi Trudy, this tool traces a paternal line from human origins to any SNP.
http://scaledinnovation.com/gg/gg.html
Choose: Tools - SNP tracker - enter your SNP - GO

Hi there
I took the National Geographic test while ago and I am pf7263 and it says i am 72 % Anatolian. I can trace back my linage to 16th century alevi poet and a rebel who was hanged by ottomans.