I prefer the 71-4 blocks that have the more "normal" deck height. They are the same strength though as the 351W's didn't lose the extra weight until the end of the 1974 casting run. Casting numbers from D1OE to D4AE will be fine. The third "digit" of the casting number denotes the car line, i.e "O"=Torino, "A"=LTD or Galaxy. It doesn't really matter which vehicle the block came from, as long as it's in the correct year range. Here's a pretty good link to older casting number identification if you're interested. Casting Numbers
.... it wouldn't be the first time reality took theory and conjecture out behind the woodshed and gave them a good thrashing.