Unfortunately, Sheldon wasn't quite right on this topic. I've had about eight Super Course framesets pass through my basement in the last few years, all from 1971-73 (i.e., all originally with cottered cranksets). Some had 24 tpi bottom bracket shells (such as my current '72), most had 26 tpi shells. That's why Phil Wood Co. labeled their 26tpi rings as shown:
Neal