Hi,
There could be plenty of options to design this network.
I am not sure the capabilities of the existing switch but if you want to stay with HSRP I can think of :
BFD with HSRP for fast failover.
HSRP load balancing by using separate groups
Object-tracking.
Aggressive timers, preempt, priorities
Routing protocol (OSPF, EIGRP) with BFD will help to get msec failover.
Regards,
Nazim