when I get the new extensions in a couple days I will see how well they thread into my tapped holes. If a little loose I will put red threadlocker on them and maybe I wont live long enough for the ignition coil to fall off again. Otherwise as you said some re engineering or maybe a visit to a welding shop to weld the holes shut and re-drill and tap again.
If Tecumseh had made those posts 3/4 in longer coil could attach directly like every other small engine. Seems they found a flywheel with magnets too far from engine and they had to adapt. 10-24 threads are a bit small to hold this heavy coil. Any vibration and I could see this failure again. Wont have all the parts until the end of the week so I can see if it will run again.