I hate to tell you this, but you shouldn't build either motor. I think you should just sell that Roadrunner to, I don't know, me?

Seriously though..its all personal preference. Some people are purists and belive numbers matching is the way to go. My Chargers, Roadrunner, Coronet R/T are not numbers matching...but its hard for anyone to look at the numbers when I am blowing by them like they are standing still. Decide whats best for you...but if you are on a budget, build the motor you have with some nice yet inexpensive speed goodies, and watch out for the flashing red lights in your rearview mirror!