350 Engine Code?
Ok, It seems the numbers and letters you posted go nowhere. You know 3970010 is either a 1968 327 block and a 1969-1979 350 block. You will have to get some other codes to figure this out. The small block Casting Date is located on driver side rear of block on flange forward of bellhousing. Here is a Casting Date Example: E038 - (E = Month, 03 = Day, 8 = Last digit of model year (1978)). Find your casting date to see when the block was made. On the left-hand side of the front of the block there should be some more letters and numbers before the suffix LYC. Look for a letter followed by 4 numbers then the suffix code. I am thinking that suffix code is TYC. Measure the mains to eliminate the 327. 327-2.3" and 350-2.45". Sorry I can't be of more help.