Ask at Mars Metals,
4130 Morris Drive
Burlington, Ontario, Canada L7L 5L6
They've casted most of the new and replacement metal keels in the US from what I've heard. If you have dimensions or can take them from the remains, Mars can probably cast you a new keel or tell you how to go about having one made up locally for less. They're very up front about letting you know when they are *not* your best choice, too.