Hot Rods 40 Merc transmission options

I have a 40 Merc Convertible I want to convert to an Automatic what Auto trans for it is recommended? I also would like to know what else do I need to make this happen?

 

What Engine Are You Running Now?...

 

If you have the pre war flathead, the only option is a C-4 conversion from Flat O Matic. And a lot of cutting and fabrication on the center of the X member. And reconfiguring the rear axle since you are removing its method of location (torque tube).