727 or 904?

I currently have a build 904 in my dart. The trans has a broken band (i think) and I need to pull it out to get it fixed. I also have a 727 in my basement. Is it even worth trying to fix the 904 or should I just build the 727? I would also like to NOT have a manual valve body. I like to just put it in drive and go but open to suggestions. The car has a procharged small block that makes 550hp. Thoughts?