I own one and know of one other. They are hard to find. I did the math once for a display of my rifles, of the number of /2's made, based on the 10,000K or so, and divided into the number of /2's produced, with the known number of other makers models of Mk1's, included into the calculation. Based on this, one could project that less than 3% of that 10K was converted, and that number is 285 rifles.
This is just mental gymnastics, and has no backup in any history, other than the known production rates of the No.4 and /2's and /3's.