I own a 1970 GTO, I am having a hard time identifying the engine. The block stamp on the front has a WD which according to what I have is either a 1967- 326, 1968- 350 or a 1973- 350. The block mold number is 9799914, making it a 1970 400 or a 400 RA III. The date code by the distributor is 0815. All numbers sheets I have come from YEAR ONE Pontiac so not sure if they are accurate. So my problem is I want to rebuild the engine but I'm not sure what engine I have, can anyone help.