[Hib Halverson]

My data shows the FHA spring was not used on a ZR1, but never say "Never" as according to Marc Haibeck, a lot of ZRs had FHAs

The FHA spring was 93.1 NM/mm which converts to 525 lb/in.

Here in the States, there are other sources for used Corvette parts than eBay and some of those vendors might ship internationally. Use keywords "used Corvette parts", "Corvette salvage", "Corvette dismantlers"

"J&D Corvettes" in California and "Corvette Recycling" in Utah are places to start.

Neither of those Zip Products springs will work as the base spring is likely a 22173028 which is 60 N/mm and the "sport" spring (out of stock) is likely an FHB at 115.5 N/mm.

If you can't find an FHA used the FSK may work