This car is my 71 challenger vert driver. i've got a built 440 going into my 73 for when i really want to get on it and go. so for the driver i was thinking the 650 would be fine as well, figuring it would be close to what the factory used. when i do rebuild this it won't be much more than 450 hp or so and i don't plan on racing it as thats why i'm building the 73.