How about giving it the drawback that all

draw spells have? Life loss.
Contract from Below

Sorcery
Exile the top card of your library, then draw seven cards and lose 9/10 of your life rounded up.
I wish I could say where I heard it, who the parties to the conversation were, and exactly what the quote was, but it goes something like this: Evan Erwin asks Pat Chapin how much life loss would make Ancestral Recall an acceptable card to print. Pat Chapin thinks for a minute, and then says "20 life, and it would still be a very good card in many formats."
(I'm gonna ask my friend Adam if he knows where that's from, cause I'm pretty sure he told me that story, although I'm not positive.)
Anyway, I think the key to making some kind of workable Contract like card is that the cost should be somehow outside the game, in the same way that ante is effectively outside the course of normal gameplay.