Be careful because the Tekin ESC you have might be too old to handle a hot modified motor combined with the new batteries. That being said, I recently tried using a 10 turn Orion V2 on my old G12cIII with a GP3900 6 cell and it ran fine, but I don't know how much more it would be able to handle.
Another thing, Tamiya's lightweight reversible suspension won't fit most foam tires without modification. There have been many iterations of the TRF415, and the oldest one did not come with the lightweight suspension (I think it came with the TA04 style suspension).