Dan,
VAR tools (FR) had once made a #932 "Extracteur Universel De Manivelles" [Universal crankpuller]. This was basically a billet which clamped on around the outside of the crank arm. This had one bolt which pressed against the lower (pedal) end of the arm to help keep it parallel, and then a long extractor-type bolt fitted with a very long turning arm (for applying lots of torque) screwed down into the crank and pushed out the spindle. The threads were all on the extractor device itself. ~ But, good luck finding one of these gems!
As for Stronglight threads, they were indeed a bit larger... but only slightly. A TA dustcap would thread in, but rest very loosely in a Stronglight crank. So, I assume the threads were the same metric pitch. Stronglight (I believe) was 23.35 mm x 100 and TA was 23 mm x 100. So, "IF" you can find a VAR 22/2 or an actual Stronglight made extractor, you "might" try to use it to slowly chase the threads to a larger size. Unfortunately, I'm afraid you'll never locate a real tap with Stronglight's unique thread.
Perhaps a helicoil insert would be the best way to go... once you get everything apart. Good Luck!
Bob Hanson Albuquerque New Mexico