340 Engine

I just picked up a 340 engine and I was wondering if anyone can tell me what the numbers mean and if there are any numbers I missed and is it normal to find different heads on an engine I have a J head and a U head on this engine? the numbers are FW340P31040347, 1-7-70, 2780930-2 Is this a 1970 engine or did it go into a 1971

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