You can use the Image Selection section of the one-page to add up to 24 images, and you can organize them using the template chosen with the customize feature for grouping and alignment.
Since you want to add 80, you can also use the Insert an Auctiva Hosted Image tool on the description box toolbar (lowest bar at right). That will create HTML code that inserts in the description section for the images. That tool operates with a popup page of your images library. If you organize the images in a new Folder for each listing, that might make the effort a little easier (and keep you organized). You'll also need to set the Image Properties to control the size of the image you insert. Just right click on the image after insert to get the properties window.
Given the page-load problems with eBay's new page design, 80 images may give you some problems with the listing. Their pages just don't load well now with too many images, i.e. load time for 80 images just doesn't work well with their JavaScripted IFRAME that wants to close/resize on THEIR SCHEDULE.
Note to the Auctiva folks...it's why I'm thinking about this problem with a new design Edition of SophieBox called "Catalog". Large collections or lots that need sometimes hundreds of pics is a real problem. A good example is a stamp or coin "collection" that could run into the $thousands$ at auction. eBay just doesn't seem to care about the problem.
Danno
Edit: If you you're going to do 80 images, I'd resize them all to a size that gives a good view of the item, but operates with only about 20-30K per image. You also won't need to worry about properties to load them, i.e. they are presized to operate with the page.