One of my buddies has a
Reaper King EDH deck that is basically a
Scarecrow and Changeling deck. The changelings work well here because they trigger the ability to destroy damn near anything you have down.
I agree, if you are going Legacy, you will want to cut it down closer to 60 cards to get some consistency. I would suggest either taking the best Sliver you have and try to put a five color deck together and work on mana support OR pick 2-3 colors and keep it limited.
The other option is just make both, make and EDH deck out of what you have. They try to pair down to 60 for Legacy. The nice thing is that the more you play it, the more you can switch out ideas in the 60 card deck since you have a bunch of other slivers that fit the mold.
The only other recommendation is try to find enchantments that buff up a creature type as it is usually harder to get rid of an enchantment rather than destroying creatures. Or if you check
Archetype of Aggression,
Archetype of Imagination,
Archetype of Courage and
Archetype of Finality (there are a few others as well).