What is the firmware version for your C670 devices?
Perhaps you should consider:
a) Get ESAv for the same version of C670;
b) Load configuration from C670 in the C600V;
c) Upgrade C600V to the version on C690
d) Load the Configuration from C600V on C690
It is not easy but it can be achieved.
There is a configuration migration tool from hardware to virtual devices. The tool works for older versions of the AsyncOS through.
Hope that helps.
Regards,
Valter