They can be converted to electric choke, but it's really not cost effective, and involves some modification to the carburetor.
The best deal is to replace the choke coil on the intake with an electric unit. This may involve having to make a different link up to the carb, but overall the easiest way to get it done.
Those carburetors were truck units, not Marine units, and are excellent carburetors, the only early style divorced choke models with the single main airbleeds.
We sell SR and HP kits for them, and tuning parts, choke pull-offs, etc.....Cliff