>>3460571I just searched in Japanese, this blog has most of the covers and backpages. Haven't found a site with full catalogs, though.
https://matome.naver.jp/odai/2135675487740120601The ones labeled 【表紙】 are the front covers, ones labeled 【裏表紙】are the back covers. Some of them have multiple versions. Most of the back covers from that era seems to be ads for a printing company called IC, like this one from C41. But there's also ads for movies, computers, etc.