Well if you would like to have anything done properly you will have to put in a better quality floorplan, with details that are at the very least good enough so we can read out the measurements on the given plan.
For a proper design i need to know how many bedrooms and bathrooms you would like. What architectural style? sq footage? special rooms? Would you like only the garage and main hallway walls to stay and change everything else?
For your "dream crib" need to know: design preferences (contemporary, traditional....etc), any particular function in mind for any rooms (guest bedroom, children's room, man cave.....etc). These answers will go a long way in designing your ultimate pad. Does the kitchen remain in place or does that receive a makeover. Same for bathrooms. Any picture of the space available?