As I recall, the nut isn't tightened with any force. It only adjusts tension on the steering bearings. The top clamp is what locks it in. So when you want to adjust steering head bearings, loosen the top clamp at all three points, not just the stem. It needs to re-position itself and can't if it's not free to move.
I think most guys use a drift to adjust the nut because it takes a very thin wrench to reach in there. I've seen the evidence.
I just worked on a 97 Cali and it used a hex nut, not a slotted ring.
So to answer the question, it looks like the correct tool to me if yours has a nut, not the slotted style.