If the "67" 273 heads are done, they sound like you are good to go.? Nice cam. The 318 valvetrain is simpler while the 273 valvetrain is adjustable and will require 340 6 pack pushrods. I like solid cams myself but I would not change what you have since it is already installed. Right now you are only looking at a head swap? You can run the 318 valvetrain now and try the 273 in the future.