Any reason why you are wanting to change the VXL system?
May have a hard time fitting a 42mm can into the Rustler. That setup is for a 1/8. For $199 you can get some pretty good setups. Are you planning on running it on 2s or 3s? If 2s you could go around a 4000 - 5500kv setup. Can get a Castle Creations sidewinder combo with 4600kv motor for $111 or the Mamba pro setup for $195
Amain Hobbies - 4000kv Combos