modifying stock shifter for TH400 RMVB

Now my second question is I want this so that I have to push the button to shift from 2nd to 3rd. Can I just add a notch in the plate right where 2nd gear is so that I have to push the button down to shift into 3rd gear on the TH400? Like I have drawn in this picture. The shifter is in what would be 2nd gear on the TH400 so can I just cut a notch up into the metal?


