Looking good. You can track the changes to the CG inside Solidworks but I suspect that putting an OB on a bracket will almost completely offset the removal of the two I6's with drives. Some of the new core materials are about the same weight as balsa; using them for the stuff up front will help keep it from getting too fat. If you still have to play with balance, a 20-30 gal fresh water tank comes in real handy and you can put it wherever you need - you might even be able to put one inside the bracket.
