".......A '57 with a SBC???? Been a gadzillion of em with headers over the years. Check with Hooker, Hedman, or any of the header manufacturers........"

Dave's right on the money, and I'd wager there may even be more 55-57 Chevys running around with headers than there are that are still running stock manifold I've done a few sets over the years and there are several different configurations including; "standard" long tube, big tube race headers, tri-Ys and shorty (to include cast and tube type).

I don't recall the installation on the 57's really being any more difficult than any other header installation, they can all be a giant PIA, sometimes involving loosening motor mounts, minor clearancing of header tubes etc.

You might try a tri-5 site and ask them what header brands people have had the best luck with (I am NOT trying to run you off here, this is a great site with lots of information and everyone is welcome).