440 swap

why not use a motor plate and cut the mounts off for more clearance
Because the question from Saezell88 was "How does one modify a slant 6 k frame to accept 440 mounts? I’ve heard the k is strong enough but how do you do it?".
You can run a plate if you want to, but not everybody likes them on a street car. Clearance at the motor mounts usually isn't an issue. But that wasn't the question I was answering.