I using 60kg total (132lbs) for about 3 sets of 8. This movement is more difficult if I go heavier the form goes, I only do it about every three weeks. Sometimes I do sets of 5 with about 145 lbs or 155lb.
One of the most demanding exercises for sure, get stupid looks of people in the gym, who a. think what the fuck is he doing, and b. thats not very much weight. Of course they have never tried OH squats.
I was doing them every 8 days for starters and noticed a good increase in strengh rapidly, I started with just the bar and they were rock hard for me....and I was squatting over 500lb for reps at the time.
I had to start with the heals on 10lb plates till my flexibility improved. Used to wake the next morning with appauling calf soreness too. Cramps too, even though taken taurine,potassium and magnesium to try and avoid them.