If you've already got the equipment, that's okay - I would, however, recommend that the Master and Backup nodes are the X460-G2s. The standby nodes being X440s will be okay.
Now, the X440-10G models don't have "native" stacking port and will need to use the 10G ports for alternate stacking (aka SummitStackV), thereby using up your 10G connections on the X460-G2s. It sounds like this will be less than ideal in your situation 😕