Cisco Switching/Routing :: 6509 / Provide Internet Redundancy To Local LAN User Running In HSRP?

One of our customer ,  where there 2 6509 switch , one is Core_sw1 and other is Core_sw2 , catering about 32 Vlan , and HSRP in running for all Vlans , till here no problem , now there internet Router which having one Internet link , which connected and configured on Core_sw1 in a way that one interface of Core_sw1 is given Public IP and there is vlan 85 which internet vlan and vlan 85 ip are natted with that public IP with one simple static route given toward internet router , this is how internet is working ok.
 
Now i have configured  vlan 85 in hsrp as all other are , how can give redundancy to vlan  85 user , that if Core_sw1 get down , internet traffic can get out through Core_sw2.using same internet router with single internet link .i am not talking of ISP redundancy , but Vlan 85 in Core_sw1 goes down , other Core_sw2 will server internet.