Size of Pedal Threading on old German Glockenlager?
Just try chasing the threads with the normal taps (remember the left side is reverse threaded) then try the pedals. Sometimes just chasing and cleaning will be enough, and what have you got to lose if the threads are already damaged. Some pedals have a longer section of thread than others, certain pedals may work better or contact the intact threads better.

Otherwise there are insert kits that cut a larger diameter hole then insert a brass threaded part that has normal pitch threads on the inside. These kits are expensive and may only be made for aluminium cranks so check that out first.