Hayhugh posted a link to a slotted CC grip set by Sile -
https://www.gunpartscorp.com/ad/985140.htm
That looks interesting. I'm not familiar with Sile grips, but a set like that with an extended magazine button in a left-side milled-slot magazine might be kind of cool...
I don't know how you'd get a window insert in the grip though...
I can see one issue - Does Sile offset the slot like the original CC grips??? Or are they centered to the follower button centerline??? If they were offset then you could mark the magazine itself with the graduations instead of that added metal strip the originals had in the grip...