Based on Ike 2008's MCP of 935mb that would equate to a max possible surge of 19.5 feet.
Landfall windspeed maximum was 95kt or 110 mph that would roughly give a surge value of 12 feet.
Ike's surge was in the 12 to 19 foot range. At 99% of locations.

I use the Storm's lowest barometric pressure to calculate the maximum storm surge. Worked with Katrina and other Major Hurricanes. It's the worst case scenario... but gives a lot of margin for evacuation of lower areas.

Always use the storms lowest barometric pressure reported and you can't go wrong... or get wet.