To be honest just giving a flying wing a single engine non afterburning WS-10 would be a rather major increase in capability and size from GJ-11 which uses a non afterburning WS-13/21 class engine.
Two WS-13/21s is probably better off just going for a single WS-10, and if you need more than a single WS-10 then you'd be getting to WZ-X size category.
