Engine out performance is not a player in the manner in which you are thinking.
An aircraft must be certified to make a 2.4 percent climb gradiant with the failure of its most critical engine. The concorde, 747 a340 etc are certified to lose 1 engine and make that climb gradient. They are not certified to lose 2 engines and make that. Depending on weight, a double engine failure in any 4 engine aircraft right at v1 may very well be fatal. They aren't required to be able to do it.
A twin is usally more overpowered in normal state because they have to lose 50 percent of their power (vs 25 percent for a 4 engine aircraft) and still climb.
So it will be by certification requirements no different then a 737 in the event of an engine failure...
Cheers
Bohica