Trim only a notch about 1/16th by about 3/4 in length.
the job is done by carefull filling of C-803 , one part below WD-814 and the inboard part above.My C-803 extends forward above the WD-814. I trimmed the C-803 so it sits flush to the mounting surface along the entire length. I used a band saw and then cleaned up the edges. This took about 5 minutes to do both C-803s.