converting 340 to EFI is Edlebrock the best solution?
Another option to look into for a wiper motor is a late model wiper motor plate off something like a 1985 or later Diplomat and the motor from a mini van.
73' B3 340 Duster pro touring build
It is still a 2 speed motor and the wiring is the same same but you will have to splice the wires since the plugs are different. The one unknown is, I don't know about the arm. I think it will work, but I didn't get mine mounted. I remember looking into it and I think it would work, but not sure.
Motor kind of looks like the below, but would be oriented differently.
Based on the posts following the one linked above, sounds like
@moparmat2000 might have done this in the past?