I don't know how to convert Amazon listings to eBay, but I know you can use a software to manage both eBay and Amazon listings. Visit this: https://www.sixbitsoftware.com/
This software is originally designed for eBay sellers, but the developer just added Amazon integration functions to it, though it's still in beta and should become official soon. To get more information about Amazon integration, contact their customer service, or visit the forum: SixBit Support Board
You need to register with the forum (free) to see all the announcements about beta release.