hmmm strange... here are some pictures of my 3 MEU's side by side. All grip safeties are interchangeable.
2 black are stock, silver is a nova which i assume to be similar to yours.
The nova had to be filed before it would fit. Maybe compare the image of mine to yours?
Black with wood grips - guarder
Tan - hurricane
Other black one is a nova
From the photos you can see that all 3 frames have the indent or lip/ledge as yours does. I have a strong feeling that you should need to file the grip safety to make the 'notch'
But maybe someone else can chime in -- Illusion maybe
