You can also accomplish the same sear adjustment with your pistol grip screw -- I believe it was my Ronin Grip where I originally had the screw so tight that the sear wouldn't trip... Figure out the screw threading and then you can just shorten it with a file to the point of perfection (and maybe a little past just for reliability assurance).
Unless you're a lefty, I can't subscribe to the trigger guard dremeling.. There are ambi mag releases and other aftermarket mag releases that allow for easier access to the mag release w/o cutting. And the protected mag release was a later upgrade mod to the VZ58 after the unprotected release, presumably, caused issues in the field -- after they switched from the single loop to the split...
Sear spring you could have just bent the left one down instead of cutting, which would have effectively left a "spare" inside the rifle. The reason you see some single leaf springs for sale is that it was a modified component required for approval as a non-automatic firearm in the many various countries where the semi-auto only version of this weapon is legal for civilians... I do not believe it's required in the US, and if it is, it's only in the import configuration for the VZ58 sporters.