You know, there'* a much easier, and cheaper way to prevent the fans from getting too close.
I too have SD headers on the Regal. The way I got around the clearnace issues is by using the fan assembly from an Oldsmobile Intrigue with the LX5 (Shortstar DOHC 3.5L). Due to clearance issues with the engine, the primary fan is 1" less deep than the ones you have, and they should also bolt right up. I got mine for $42 at a junkyard.
Part of the reason why I opted to go with the different fans was because I also didn't want to get the header wrap wet while driving through puddles, get salt stuck to it, and get salt trapped inside the header wrap. I know they're stainless, but I'm not taking any chances because I had to have these bent to clear the firewall.
2005 Pontiac Bonneville GXP - For Sale ----- 1995 Buick Regal GS(X) - L67 madness
2000 Buick Regal GSE - Stock...for now
----- 1987 Jaguar XJ-* V12 - 12>8