JFRICK is right, SG as such a thin body that you could be loosing a lot of it's original tone and sustain. You cannot compare a SG with a Les Paul. Les Paul is a lot thicker. And locking nuts, dude don't screw around the head of an SG it is so fragile, mine was broken in transport and I know a handfull of guys that had the same thing happen to them.
Look at most mods done to SG regarding trem. They don't use floating.
Anyway, take my advice or not but for the price you will have to pay for this mod and the risk you will take, do like I did, buy another guitar with a floyd. Guitars are engineered a certain way for a reason and altho upgrading is cool and all, messing around the core of a guitar is dangerous. That's my point of view anyway.