I have stopped seeding the older individual issues in favor of seeding the full year releases. You can find these on Mininova:
Nintendo Power 1988 CBR
Nintendo Power 1989 CBR
These releases contain all of the older issues to which you are referring. If you only wany certain issues, most Bittorrent clients will let you specify which files within a torrent you want to download.
I will continue to seed these as well as the other releases that have not yet been incorporated into full year packs.