Cardboard boxes are not the best storage option in Hawaii.
I'd wrap each piece in a couple layers of butcher paper or newspaper, and spray the items and paper lightly with a rust inhibitor. Hawaii loves to see metal rust!
The wrapping will prevent damage if it's thick enough. No need for the Styrofoam. If the paper isn't enough for the heavier pieces, bubble wrap works great.
For a container, I'd pick a plastic storage box with enough of a seal to keep dust and insects out. You could also place some desiccant packs inside it to help keep moisture down. Placing the parts in a tightly closed plastic bag would also help keep moisture, dust and insects away.
In short, you can probably come up with a better way to store the 550 than the original factory carton.