The MCHG grippers will both mount onto RoboTool Part #RTI-GMB-230. This is a simple flat plate that can be customized to fit almost any mounting pattern desired.
It is also adaptable to the Round Stock Gripper Mount that RoboTool offers, Part #RTI-RSGM-50.
The RTI-GMB-230 also comes in the following configurations as a Post Mount, which can fit into any 1/2" clamp hole: