That's what we were running with the USFS in the '80s. The red ones. You had to cut the clutch cover a little to use the clearing bow bar.We could put a bow on a Stihl without cutting the clutch cover. I remember a time here when an XL12 with a bow was real popular.
The guards we used were simple strips of aluminum, with bends along the long axis. They were bolted to either side of the bar. The bends offset the part of the strip that was along side the chain for clearance. The edges stuck up above the chain. With a strip on both sides, to get to the chain you would have to stick something down between the strips. The guards covered the run along the bottom to the stinger and along most of the top of the bar. I've not seen a pic of a bow bar set up with that much guard. You can only cut with the nose, but that's what you're supposed to be doing with these bars anyhow.
One time I was stepped back while cutting and tripped over something. I landed on my butt with a running saw in my lap. Between the guards and the chaps and my habit of taking my finger off the throttle when not cutting, it didn't end up tragic.