Craig,
On my 7KCAB the diameter was 3/4". I bought teak wood pistol grips but they didn't fit since there is a small curve in the stick. Instead I went to a bicycle shop and bought a set of mountain bike grips and used them. Lubbed them with soap and they slipped on easily. Best grips I have ever felt, especially during acro. Cost about $15. Mounted the PTT in the center with the use of a washer that I inserted in the grip before sliding it on the stick.
Hope this helps,
Dave