I have a BM visor in my MS1 helmet, and since the size/measurements are pretty much identical, I'd say it would fit a Sgt. Fang.
It's a really nice product. It looks really dark from the outside, but vision and clarity are great when you're wearing it.
For the green visor, just use a welding visor replacement. It is green, yet looks black from the front and it quite dark. You can get them from welding supply stores for under $10 usually, and are thin enough you can cut them with a pair of scissors.