shopruger.com lists one part number (looking at the Williams FO set) to fit GP100, Redhawk, Super Redhawk, and Super Blackhawk Hunter. I have never stumbled across any information that would suggest there was any other spec that could be mistaken for a GP100-compatible front sight that wasn't the right one.
The sticker on the box says FB00018 and the part looks just like this one https://www.midwayusa.com/product/1005925014, which is listed for both the GP100 and Super Redhawk.
I may just go all Tom Givens on the existing Ruger sight, since I have the stuff sitting around already.