need help on swaping a 2.8 into a 3.1

got a start up problem with my cavi and it has a idle problem as well as thy all do....it has 230000 on the motor and i supnt a bearing so i decided to swap a 3.1 in her....the tranny slipps badly and i got a tranny motor and ecu on the way...........im asking for some help on how to take on this quest....ne advice on how to do it is much appricated