In skipping through the thread, the W* code blocks are manual and the Y* code blocks are auto trans. IMO don't worry about finding a correct code block. To much time and money will be spent trying to find one. Ask me how I know, a '69 WZ block is as rare as a hens tooth. I settled for a WT (GTO) block.
The original specs of your motor don't mean a thing other than the original CID. What it was rebuilt with is what counts.
