As my mechanic Uncle Joe used to say, "Proper tools give good results". Which I never fully understood til I met this one girl...uh never mind, a story for different forum.
Back on topic, the '86 Ironman came with that style Headset. I used a rag and huge wrench. It works , but be careful as it doesn't take much to jack it up.
BTW, I ended up replacing that headset with a standard style nut, but if I were you I'd get the correct wrench if I planned on using the star style nut. Because when you overhaul headsets and it can get tricky. Too loose and there's a chance (after many miles) of ruining the headset. Too tight and it's like riding a unicycle and I don't know how to ride a unicycle. But for most DIY wrenchers that's the fun of it. You get it just right and you feel confident about your build. Ultimately you should get the correct tool.