4 speed 4 door

I've been collecting parts for a few years to 4 speed swap my 360 powered 68 4 door dart. the only sheetmetal you should need is the 4 speed hump. If you want a bench seat then you will want to look for shifter handles specific for mounting with a bench seat. If you want buckets then your options are completely open for handles.
For the trans try to look for a slip-yoke output shaft trans. The early a body style (don't remember the name off the top of my head but has a 4 bolt flange instead of a slip-yoke) won't work because the speedo cable is different according to the good people at brewers. I believe the slip yoke started in '66 so you would want a '66 or newer trans
Then pick a bellhousing that uses a 130tooth 10.5 inch flywheel. There is a cast iron option and an aluminum option for that. Just make sure they are for 4 speeds (The aluminum bellhousing has both 3 speed and 4 speed bolt patterns threaded in from the factory)