The bigger the better, but will probably depend on what you're willing to do as far as oiling. A 700 hp 540+ inch motor is easy and will be really mild. A 150-200 plate on top of it will easily do what you want to do.
When you get bored w/ it...put in a real cam and more head work. Then put the man jets in it.

My sled isn't as heavy as your car, but could probably be used to somewhat gauge your combo off of.