Small Block 727 question

Nothing stoping you, grab it. Be sure to grab the flex plate and you will have to knock the weight off the torque converter to work with your 318. Crossmember is the same.

^^And does your Duster have a console? If so, you will need a transmission with the "underneath" holes for the shifter shaft support. These are at the bottom of the transmission tail casting I think just in front of the mount