The keystone badge toms are definately 3 ply. If they are 68 or 69's, they should have a clear interior. The white paint in Ludwig shells switched over to claer maple around March-April 1968. The other drums are most like 3-ply but Ludwig switched over to a six ply shell around 1976. What color is the set? I am sure they will sound pretty good.

I read that Bun e Carlos said that the late 60,s early 70's 3 ply clear int maple /poplar / maple shells were the "ones",the later three plys had the grey/speckled granitone interiors,some say they did that because they were using up mahogany interior shells and wanted them to match,I have owned and played the later granitone 3 ply's and they were great sounding drums,some people feel those shells were as good as anything ludwig made.Don't be suprised if the kick or or lower rack has a clear maple int,I bought a luddy B/O kit new of the floor in 77/78,and the two racks and kick were clear int, while the ft was granitone.

You'll want to check out the edges/ends of the drums for wear, esp. if they're missing hoops. Sometimes there can be some ply separation, out of roundness, or worn bearing edges. Otherwise, all the eras that I've played that you're talking about sound great to me!