Now is the best time to add Silverore to MC, because after the 1.2.3-Update, we all have to start new Worlds, and new Worlds = newly generated Landscapes, so why not adding Silverore at that time?
If you add Silver it should be much more rare as the Redpowervariant, because Eloraam generates too much Ores of any kind.
If you still dont want to add it as ore, then you could make a Silvercrop, which drops Silverdust (that you already have in IC²), and a Silveringot to have the smelted one. And a Silverrecipe for UUM would be usefull then.
Edit: look at my other Thread to know what it can be used for.
And again everyone, who complains Silver does not belong to IC², gets shot, because that is obviously a suggestion to ADD it to IC², while it's possible!