You are correct. The D is for the decade of the 70's and the 1 is for the first year of the decade. I'm guessing that the WF in the lifter valley stands for windsor foundary but I'm not sure what the S stands for.
I had a 351 bock that had a C9OE casting but had D0OE heads. I think it was an original combination. It was probably an early 1970 engine.
Post the date code on the block, it's a number/letter/number combo, next to the casting number you listed (D1AE-6015-EA, that will be the only true way to determine the actual year the block was produced.
