Since when did the 401 become a short shank machine?
The 201 is a short shank machine, but the 301,400 series and 500 series are all slant shank. As bkay says, the 301 is straight stitch machine and the 401 is a zigzag (swing needle) machine. So the feed dogs and feet won't line up correctly. However if they are feet that are for straight stitching only, they will probably work just fine on a 301 as they are set up for the needle in center position. It would not work the other way, if you put a narrow foot for a 301 on a 401, you will likely have feeding problems.