Shim for One2Flush dual-flush toilet system

The One2Flush dual-flush system is really great, but I ran into a problem when I installed it on my toilet. The system does a half flush when you pull the toilet handle down, and it does a full flush when you pull the handle up. Unfortunately, the ancient Universal-Rundle toilet in my house has the lever mounted very close to the top of the toilet tank. I wasn't able to pull the lever up to engage the full flush without hitting the top of the tank.

So, this is a shim that moves the handle out