Maybe I'm misunderstanding you but I didn't mean to say that this version should work on both python 2.x and python 3.x. Ideally, there would be a PIL distribution for 2.x only and another one for 3.x only.
I don't know what Fredrik thinks, but I would not consider this ideal. Ideally, there would be a single source that can be installed to both 2.x and 3.x. This is much better than two source trees, as the latter would require porting of changes back and forth.
The only thing is that people (myself included) will only be comfortable with the PIL for 3.x version if it comes with the blessings of Fredrik, i.e. if I were you I'd try pushing this with Fredrik.
I don't think a GSoC project can possibly help with that.