The thing that sticks in my mind here is that the OP has told us that the airplane has flown with a DLE 85. This tells me that the airplanes CG was correct with that engine. Some of the suggestions here and including the OP thinking of going with the Roto 85 4s are much heavier then the DLE. Obviously this is going to lead to more work getting the CG back to where it was with the original engine.