I am surprised that more people wouldn't choose Jayasuriya in their team. I haven't seen to many greater match-winners in this form of the game. I understand that Tendulkar has the more complete record, but he has never been the game-breaker that Jayasuriya was. Seeing as it is only a hypothetical scenario, I think you could probably move Tendulkar down to number 4, a position he has occupied at various stages, in order to squeeze Jayasuriya in at the top.
If I was the opposing captain, an opening combination of Gilchrist and Jayasuriya, with Viv Richards coming in at number 3, is the top order that I would most fear, because all of those guys could simply rip the game away from you with an hour of brilliance. If two out of those three got going in the first 15 overs, then the game might be as good as over, before it even begun.