[Mr Gazza]

Monster and SS mudguards are interchangeable, but there are two types of forks used on both models.
You most likely have 45mm centres between the mudguard bolt holes on the forks.
They later changed to 65mm centres and used plastic bands that clip round the leg bottoms.
You can make a simple dropper bracket to pick up the errant hole. I think that can be done both ways? I think it's the bottom hole that's in the same position on both variants?

I have an early SS mudguard if you want to go that way, but it will need a small repair to a little crack where they all go! It's Red I'm afraid.
Equally an earlier (pre 1999) Monster 'guard will fit.