Hi
As far as I know, all A's had 19 inch wheels. Why not just match whatever your front wheel is, if its a single side go for a QD rear, but the frame / Rear brake linkage will actually determine what you use. Full widths were used with the crossover brake linkage from 58 on and were ok, but were prone to going oval on the drum when the wheel was re spoked. But that can be skimmed out.
HTH