And don't forget the main reason for the six in the first place: better fuel economy, which means that you can drive the car more for the same cost. That may or may not be important to you but that's why I'm replacing the 400 with an OHC in my '69. I want to use my car every day like I used to when gas prices were lower.

Neither combo is stock but I have the numbers matching drivetrain in the shed.