Another posibility would be the complete rear axle from middle thirty’s Ford truck they may have a lower numerical ratio. I think the bell on the torque is compatible and brakes are rod operated thru 1936.
Check, don’t take my word on this!!
Alternatives would be a Laycock or BorgWarner overdrive unit. I have both both. They fit in the torque like a Mitchell. The Laycock shifts with a switch. The BorgWarner offers “more” overdrive but requires more controls and has a position where it will freewheel
This site probably lists people...
If your running an electric fuel pump don't forget to install an inertia switch to shut off the pump incase of an accident. Late model Fords used them to shut off the pumps on fuel injected cars. I wired mine to not only shut off the fuel but also a solenoid valve in the fuel line.