The Cool and Wow factor is there with the Hemi and the 440 6 pack. Your car sounds pretty nice just the way it is.
Like the man at the Parts Counter says, "If you wanna to play, you gotta pay!"
For the Hemi conversion, you could buy a new car, pay down your mortgage, buy more investments, etc, etc.
For some that's a big deal, for others it's not.
If money is no object, do both the 383 and Hemi, and swap engines every couple years!
It's your car, enjoy whatever you decide and do.