I bought a complete FAL spring kit from Midway.
It was pretty reasonable IIRC it was @$12
I figured if I'm going to do a build, I might as well start with new springs. The nice part is that each spring is individually packed and marked. As I used a spring, I put the old spring back in the pack and resealed it.
Now not only do I have all new springs in my build, I've got a spare which is easily identified.
A lot of these springs look very similar, so this is a big help. Best 12 bucks I ever spent.
Edit; I just checked the invoice the spring kit was only $10.79