Nice work LT, I am glad you could put that dead switch to good use
if I am reading the EWD right the diode only carries the current for the small holding solenoid in the switch, not sure how much current that is but cant be much? I would be very surprised it it was over .5 amp (500ma) and is likely much less, a larger rated diode than needed would be ok you would only run into troubles if the diode was to small for the load, it would be interesting to hook in an amp meter into the circuit to see how much current is being used?
diodes are electrical check valves they all function the same the only spec are the load it can carry (.5a?) and the voltage it can withstand, 12 to 16 volts