I'm still waiting for the lug nuts, however in the meantime I made a tool that allowed me to install the adaptors to the front rotors. I filed a 1/2" allen wrench until it would fit the lug nuts, then I cut the end of the wrench off and hammered it into a 12mm socket:
I torqued the nuts to 80 ft lbs in three steps and I used Loctite on the threads. This time it worked like it should.
However the nuts I ordered to replace the broken ones still didn't arrive, and even a new problem occured
The adaptors for the rear axle can't be installed because they interfere with the raised surface of the brake drums around the center opening. This keeps the adaptors from sitting flush on the drums:
Of course I want to replace the drums with disk brakes one day, but for the moment I want to keep it this way because the conversion will take me another 4 to 6 weeks and I finally want to drive the car.
So what can I do? Is it save to machine the adapters to fit the drums? This would mean to remove material in critical places.
Did Ford ever make drums with flat surfaces? The drums are 10" inner diameter and have the standart Ford bolt pattern (5 x 4.5").