Looked at the newly acquired T160 parts. Someone asked about positioning of the kickstart lever, sitting angled back too far. I made a quick comparison of the two lickstart shafts and gears. From this picture you can see the notch for the cotter aligns differently, the T160 with the leading edge of the gear spline and the A75/T150 with the rear edge.
From the end view you can see the spline on the A75/T150 shaft points to the 15th whole tooth. The T160 spline points in between the 17th and 18th tooth.
The distance from the peak of the tooth to the centre of the shaft is 1.580" on the A75/T150 and 1.755" on the T160. A larger diameter gear on the T160 which means a smaller gear on the mainshaft (unless they moved the location of the kickstart, which I doubt).
The A75/T150 gear has 17 teeth, the T160 has 18 teeth.
The A75/T150 gear has 57-2169, the T160 has 57-4117 cast into it.