63 904 kickdown linkage adjustment
(whips out the 63 Dodge FSM) Ok, first off, these are a bit different, its a TF 6 and a TF 8. If you have a V8 in a Dart, its not original, if my memory serves correctly. So you'll want to be sure the throttle linkage is (or isn't) the original stuff, which is very different than the V8 linkage of later years.
After you figure it all out, here's the basic thing you need to know:
When the throttle is closed, the throttle lever (kickdown) on the trans should be all the way forward. At WOT, the lever on the trans should be all the way back. Somewhere in the linkage, accomodation should be made for the throttle to be able to close even if the trans linkage gets stuck.
Fire away with further questions if need be.