Change 65 dart from A904 colum shift to a floor shift

If going to a floor shift is your only goal, then get a '65 floor shifter and cables.
Otherwise:
Locate a '66 or '67 904 (must be from a smallblock if that's what you have, or a slant 6 if that is what you have. They are NOT interchangeable. Later '68 and up 904s use a convertor with a larger nose, which in turn fits a larger pocket in the engine's crankshaft. So you'd have to get the crank flange bored out to fit the later convertor, and that involves tearing down the motor. And no, you can't use an early convertor on the later 904 because they also changed the inptut shaft and spline count. A custom built convertor is a possibility, but spendy; and that's if you can find a company that can still source the correct parts to build one.
The '66/'67 trans changed to a slip yoke output shaft and universal joint, so now you need a different driveshaft- yours is a ball and trunnion setup. This will be '66 Dart only, not from a Barracuda or Valiant- different lengths. If you can't find one, you'll have to get one made.
'66 and later transmissions also changed the speedometer drive setup, the only cable you can use is a '66-'67, but that cable will also work with later transmissions. And chances are that the drive gear in the transmission won't be the right tooth count, so you'll have to figure out the right one for your rear gears and tire size and hunt that down.
Now you can start trying to find an aftermarket floor shifter that will work in the relatively constricted early A trans tunnel. You have to be VERY careful in there to route the cable so it can still function yet not get melted by the exhaust.
Oh, and you'll most likely need to update your kickdown linkage too.
All this to end up with an aftermarket floor shifter, which by the way, is still cable shifted- which literally converts mechanical linkage back into cable shift. (so technically, to "get rid of that cable crap" you'd have to graft in the entire factory mechanical floor shift linkage and brackets from a '66 A body...).
Your call.