i think a mild 360 magnum engine with an aftermarket fuel injection like mega squirt could make 400+ hp pretty easily and still be very dependable. also need to remember that the new challengers weight over 4200lbs. a small block 65 valiant is going to be under 3000lbs. that will make the car very very quick with 400 hp. i think a stock long block magnum in that chassis will walk all over a new challenger. with all the overdrive transmissions on the market now you could get some fairly decent mileage as well.
