U what u after this 6 or 8 is in the past K frame 67 or newer. the newer you can mount a 273 318 early 360 magnum. these old engine mopar superseded. to drive every day find a 67-70 a body K frame or after market mount kit;;;;
63-66 K members are the same for 6 or 8, engine mounts are different. I believe 67 up K members are wider than early A,
since they had already decided to put big block engines in those cars.