I second Zipperstop. Never had a problem or issue with any order placed.
Another thought, if you are unable to find the size and length of zipper you need in time, maybe go to a thrift store and look for jackets with zippers. You may find one the right size and length you need, at a good price maybe, all you would have to do is remove from jacket. It isn't hard to do with a seam ripper and a bit of patience. Not as good as finding a new one, but a "last ditch" approach.