4 Speed Conversion

I live in Ontario Canada. I have a 1970 340 Automatic Duster with console. But I long for a 4 speed. Does anyone have a guesstimation of what it would cost to convert an automatic to a 4 speed. What kind of shop would be able to do this? I have the tranny, petals and drive shaft from a 1973 340 Duster I used to own. Rest her soul.