I've been pondering the same thing for awhile now....
If I had the money - I'd have a custom ground camshaft machined.... As I recall, that's the key difference between an Otto and the Atkinson in several hybrid vehicles on the road at th moment...
The concern I have is backfiring... So stock setup is to spray fuel on the intake. But with a cam that leaves the cylinder open - some of that fuel fortified intake will be pushed back. Of course, under normal conditions - some fuel is left in the intake track - so I imagine it's up to the valve seals to ensure there's no backfiring...
I'm also curious as to how the manifold vacuum will change
I honestly think it's possible.... Just someone needs to fork up the funds for the cam (unless we can find someone that'll do it for free or does it for a living
). If no one does before I'm out of college (and earning some dollars), I'm probably going to give it a shot