What you might be interested in is getting a new top end built. As much as I hate the .357 SIG for Open Division, if you're only interested in playing, that might not be a bad idea for you.
With .357 SIG, you might be able to get away with not having to change your ejector, and you could use your regular .40 mags. There might be an issue with the ejection clearing a scope like a C-More mounted normally (as opposed to those funky, ridiculous looking sideways things) so you might have to consider a slide mounted scope like those little Docter/JP/CMore STS sights. Then you don't have to worry about drilling into your frame either.
Heh, side note. I just tried to look at the CMore website to find out what the STS was called...It's been hacked by some Islamic Group.