"I also have to be honest with myself how often I am going to use the car at it's potential?"
I feel this is the first, and biggest, question you need to come to terms with and work from that.
Honestly ? I don't see you getting crazy and possibly crashing the car, so using the "potential" will be minimal.
If the current engine is not easily and economically feasible to de-tune to a more un-beastly and manual transmission friendly state, pickle it and the TH and install a healthy big block and manual that fits the tunnel and will handle that power level. The only extra cost downside will be another driveshaft to handle 600 +/- hp, torque and critical speed of the rpm the shaft will encounter at the given red line of the engine. You'll always have the beast waiting in the corner for whatever the future holds.
Good luck with your decision...
