904 vs 727

I'm planning on going to an OD A-833 setup in my Duster. Specifically I'm going to try to find a cast-iron non-OD A-833 case (either 23-spline or 18-spline) and buy the Hemi Overdrive conversion kit from Passon Performance. I'm also going to run a hydraulic clutch setup most likely from Keisler. That's a few years down the road though, when I also get a good 8-1/4" rear end and build up a nice 360 to swap in. I'm taking a welding class now in school also, so I think I'll be able to do all the tunnel mods myself.