Well all the 50 series turbos including the 54 are small shaft turbos and the TE-45 is a big shaft. I am pretty sure there is no way to do this and to just change a big shaft T63E with 63mm wheel to a TE-45A with 66mm wheel it is $400 so you would have half if not more than what a TE-45A would cost in modding yours. Sell the 54 for what you can get and just buy the 45A.