I'm gathering there should be some actual angle. To figure what that is, you measure the height of the bridge, length of the neck and so on. Basically create a full scale drawing and work it out. It's not as hard as it sounds. here's a link http://www.tundraman.com/Guitars/NeckAngle/Index.cfm
Since you have already filled it in, you could easily rout it back out to something more accurate than it was.
However, it might not be worth it if you are upgrading (or you may not have a router) and shimming might be the simplest way to go. I have heard of all kinds of things beings used successfully. Definitely playing cards as Rick mentioned, also plastic, wood, brass, and even sandpaper.
Good luck with it!
...so ever since then, I always hang on to the buckle.
