Hello Michael
I’m not sure I have completely understood your topology. You have two datacentres, that both have VLAN 680, and you are running HSRP between two devices that are physically located in different DCs. This is possible using OTV, but this results in one of the two devices being elected as the physical gateay, so when you have a lot of traffic, it is oversubscribing your OTV connection between them. Does that sound about right?
What you must do is to filter FHRP messages across the logical overlay. This filtering is required to allow for the existence of the same default gateway in different locations and optimize
the outbound traffic flows so that the OTV is not used to reach a remote gateway. In order to do this, you must enabling FHRP filtering so that each DC will use the local gateway (with the same virtual IP and MAC addresses).
You can find out more information about this on Pages 6 and 7 of the following OTV best practices guide.
Just one note, I notice that your HSRP numbers in the configurations you shared are different. Those should be the same, but I assume that was a typo.
I hope this has been helpful!
Laz