found this, it isn't much other than an index, but may provide some focus material for future digging. Seems to be significance in his trip of June 18, 1951 on behalf of Truman.
sauce- https: //eisenhower.archives.gov/research/subject_guides/pdf/Korean_Armistice.pdf
also you can listen to a John Foster Dulles interview (audio) of June 24, 1951 Meet The Press interview (less than a week after his trip to Korea). The mp3 link is a little down the page found here
https:// pastdaily.com/2014/06/09/view-dulles-john-foster-dulles-meet-press-june-24-1951-past-daily-reference-room/