So Dan you are saying "early 71 Cuda shaker hoods had no reliefs" and then "most 71 Cuda shaker hoods have no reliefs".
Not sure there, and although I have not seen them all, 75% of the real 71 Cuda shaker hoods I have ever seen all have the reliefs.
The hinges also tell the tale with the different size mounting bolts, and I have seen more 71 hood hinges with 71 Cuda shaker hoods than 70 hinges.