727 trans

So if I decided to go back to a 904 what would I need to do the put one in?
Like tail shaft, drive shaft....
Or will it fit right in the 727's place?

you can use a 904 , but , you will need to add 4" to your driveshaft or find another one. you will need the yoke. you will need the converter and flexplate. also if the new 904 verter has weights you must remove them.