That must be the cousin of the 426 max wedge in the 63 Plymouth. Never knew they offered it in any other car. You don’t suppose it has the stage 4 heads on it do you.
He said you can't buy pistons for a 413 (he works at National Moparts) so that's why he bored it out to a 426. He does have a nice cam in it and will put some better heads on it. Talk about a sleeper!!