Supposedly if you already have a T series engine in the car then the 4ag should be able to go straight in. I have read that the t series crossmember allows fitment of the 4age. (at least in a KE70)
Also if you are fitting a 3t crank in a 2t block don't you need to remove some material from the block to allow the swing of the (larger) crank? Maybe it is only the earlier 2T's that need to be modified...