engine serial numbers

I have learned a lot from all you guys and your knowledge about Hudsons.I have been restoring my 1947 club coupe since last March and have saved making a lot of errors by reading your posts on many issues regarding restorations. My uncle and I raced Hornets in the late 50's in Duluth,MN and Superior,WI. I have installed one of our racing engines in my 47. I know there has been much discussion on what year different engine numbers indicate,but I have a hand stamped engine number on the left front side of the block near the top. It is F1215 can one of you tell me what year it is?

Thanks,
Chuck McDermott