Physically, it looks like it should fit the Superdome 2 (only one I have experience with), but I doubt it would be supported. The CB900s blades were meant to all work together after all, not independently. I don't think the OAs, midplane, or IOX enclosures are going to support it since everything is provisioned on an nPar level. Pretty certain only the Itanium blades supported the GPSMs too.
I know the lower end Integrity offerings (BL860c) would work in C7000 chassis, so there's some interoperability, but they had separate fabric that would go through the front of the blades instead of the midplane to link everything together.