One other thought, as you’ve changed the battery , has the new battery been installed correctly, all Chevrolets are negative ground, and has you have a history with early fords, may have overlooked this fact. ( model A fords are positive ground, even though model T fords were negative ground!!)

Once you have checked battery polarity is correct, the generator can be polarised by a short length of wire , momentarily touching both sides of the cutout mounted on the top of the generator.