I'm going to make a much better writeup of this, but for now I'm just uploading the .bk2
This should beat the current TAS by 23 frames.
Keep in mind this run was made in version 2.3.2 with the SubNesHawk core. I believe this version has a bug with IRQ timing? I don't know all the details, but it might not work on later versions of the emulator. This should not affect the run on console, so I've been told.
More info here: http://tasvideos.org/forum/viewtopic.php?t=21951