ayesakara has several long post-513 fics that are quite lovely. This link (http://www.livejournal.com/tools/memories.bml?user=ayesakara&keyword=My+QaF+Fic&filter=all) goes to her QaF fic memories thingmabobby. It's flocked, but I think you're on her flist.

If you go to my memories, practically everything in the "Fanfic100" folder is Post-513.

At qaf_anon there was a lot of Post-513 stuff. The longish ones that I remember offhand were "Coda", "Seventeen", "A Wave Unfurled" and "Blank Canvas". [(I know you prefer long stories. :)] Also check out "Love Spins Gold From Time", which was my total fave.