UGH! It's been awhile!
Me thinks the Ford 6 volt system generator field is externally grounded, so...
With the generator installed on the engine and all leads connected...
Momentarily connect a jumper wire from the 'BAT' to the 'GEN' or 'ARM' terminal of the voltage regulator.
Just a touch of the jumper to both terminals is all that is required.
IF the generator field is internally grounded instead, disconnect the field wire from the regulator and momentarily touch this wire to the regulator 'Bat' terminal.
Hope this helps.
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York