TorqeAddict...You will be way ahead to go with a mild stroker 440. If you can assemble it yourself you can stroke, machine and asssemble a 500 inch mild stroker to make 550 hp and maybe 600lbs torque for about $8k and that includes carb to pan,ignition and headers. I built this for a friend's 70 Challenger and he runs on 89 octane fuel. With the AC on it will just boil the tires in any gear.
I've been looking at every option to get 600 hp from my new SRT8 Challenger and a supercharger will be $6k alone. I will need to stroke it, ported heads cam and so on plus pay a tuner big$$$ to dial in the calibration.
If you go new Hemi you will have to redo accessory drive system for water pump alternator and power steering, rig electric fans, conversion kits for starter as new hemi is on the opposite side.
Un less you have big$$$ to spend this is a no brainer.
PS I have yet to have a new Hemi catch my 10 second wedge GTX to tell me his engine "looked cooler. I get a LOT more respect from the 10 second time slip.