Store Engines merged into existing levels

Need some assistance. I bought an engine in FAB. I had already built out the level, but without blueprints, programming, triggers,etc. Just 3d assets, BSP and lights. Can i move this into the new Engine or do I have start all over using the project that the engine makes you do? I could merge them, like any other levels, but i am afraid of breaking the engines blueprints, triggers and things i need for the game.