340 4 speed crank

If the 4 speed motor is still assembled I would check into the cost of having the automatic crank drilled. If it's not too expensive I'd just have it drilled so I could keep the other motor together. If the 4 speed motor is already apart I'd be more inclined to swap cranks. This is assuming both cranks are forged. If either crank is cast I would use the one that was forged.