Thanks for the call Paul. Other than the ATS AFX spindle, the only other suggestion I could make is that you contact Art Morrison Ent or any of the other aftermarket (sub-)frame suppliers building chassis using the C5/C6 front knuckles...just depends on how serious $$$ you're looking to get.
Maybe Mr. Matt at AME will chime in on this thread when he gets the chance.
Tobin
KORE3