Oliver,
Go ahead and order it -- if for some strange reason it doesn't fit, they'll take it back.
On the hood seam, I didn't need to replace mine. If you need to replace yours, you'll need to find one from another hood, probably. They aren't available as replacement parts. A decent used hood (or just the seam piece) for an AD big bolt shouldn't be too hard to find -- put an ad in the Parts Wanted section and maybe one of the Western gang will send you one from their vast supply of pristine parts trucks they have out there

Good luck!
If you have a hard time finding one, you can always come up here for the Stovebolt Homecoming and have the one on the Stovebolt HQ driveway ornament -- it may still be useable ...

John