I don't know where I got the idea that TA and Stronglight tapers were ISO, but like other people, some source somewhere had given me that impression. However, I just got a Sutherland's Handbook, 4th edition (1985), that has a graphic showing the relative “fit” that different maker's axles would have on the same crank. I was surprised to see that both Stronglight and TA appear to have “stubbier” spindle ends than, say, Campy, late Dura-Ace, or Sugino Mighty, and of course, ISO, which is even smaller. They also have a fairly long spindle taper (more room for the inside end of the crank, so that it won't run out of taper). I double-checked Sutherland's 6th edition (available online as a PDF), and close reading showed me that they did not change their story.

Off topic: I like the 4th edition because it has a bit more information about the components that I am particularly interested in: those preceding the late 80s. I'm thinking of PDFing the whole thing, with bookmarks and all, and making it available to the C&V population (no cost).