Yeah, maybe. I have one of those adapters. I actually made an adapter to use actual NES controllers (rather than Famiclone with Sega-style plugs) on this thing as well. Anyway, I have a disassembled Classic Controller and Super Famicom controller waiting for the operation, because I want to play Samurai Showdown Anthology with two SNES controllers, one thru the adapter and one that will be like yours, but with the Classic Controller inside.
I just want to do it and prove it can be done. I actually created a topic her a while back:
http://forums.benheck.com/viewtopic.php?f=23&t=35450" onclick="window.open(this.href);return false;