That's very likely the case, in my opinion.

Are you talking about just the inner ply? Because if I'm not mistaken, the shell composition, even up until the mid 70s, utilized mahogany. I believe the drums usually had mahogany on the outer ply - the ply directly under the wrap. I believe the construction from inside out was maple rings, maple inner ply, poplar middle ply, mahogany outer ply. I could be wrong. Also, I believe all of Ludwig's rules had exceptions at the time.

There were several reasons as to "why" the shift away from African Mahogany. The availability was reduced somewhat by the early 60's and flat out phased out by the 70's. Among the factors listed were politics, pricing, ecology, human rights, and changes in music. I'm sure there were other factors, but these are the ones that I've researched.

My 1970 kit had maple/poplar/maple. It was stained "dark maple".

Very interesting. Thanks for the input.