The motors are identical. The differences were in the intake and exhaust, but the power shortage was strictly tuning. Eurocharged has had a lot of success tuning those motors, and a 55K swapped SRT-6 is running 10.6 @ 127 MPH (highly modded though). They do remote tuning and remote dyno tuning also.

As far as the trans is concerned, it's not that it's a Crossfire specific unit. The MB manuals just can't handle the torque like AMG would want. You can mate it to a 6-speed, but the tuning involved isn't cheap. Guess it all depends on how bad you want that third pedal. All I know is I don't miss shifts in my AutoStick and can still select gears on the go.

And relax, I took no offense to anything! Have fun here, do some research, see what has worked for those that have done it before. Good luck with the build.