No, the Australian B&W on the TTA has a slightly larger ring gear than the GTA. If I remember, and I can look it up, the ring gear on the TTA is 7.785".
Not sure how it measures up to the the GN 8.5", but if it's all about ring gear size, it wouldn't be as strong. However the lower ratio of 3.29 should be easier on it than the 3.42 on the GN. One possible disadvantage is, I'm not aware that anyone offers a cast TA-type rear cover for it. Anybody know if anybody sells one ?