Is there any way to configure the Cisco 760 so that it has a default gateway of the physical BRI interface and not a next hop address, for example, to route to a PPP interface in Cisco IOS?
Yes, if multi-destination is not done simultaneously, the one WAN interface profile can be defined to be the default interface through the default static route entry: SET IP ROUTE DE 0.0.0.0 GA 0.0.0.0 As you can see, this says that packets with unknown route/destination are routed through this interface, so there is no need to know the IP address of the remote device. Because this is a PPP link, bits are thrown onto the wire and the far end does not know what to do with it.