I will make a couple of suggestions on the shift linkage; lock out the shift interlock rather than mess with redoing it. Just make up a one piece kick down like the later models had. I usually make my own from Dodge trucks in the pick-a-part yards. The key is getting the right ratio between the carb arm and the arm on the tranny. Make sure that the 727 you get has the mount on the tail shaft for the shift rod arm. You see the arms at the Mopar swap meets regularly and they are in repop, too. Is the 904 arm different than the 727 arm? Year One shows them all on back-order and only lists a 727 arm.