No way - today! Angular sensors would require to evaluate length, width and position of the MU at the same time. Plant Simulation for performance reasons only considers length and position.
This task is usually required, when you need a gap detection for succeeding MUs. In case you want to consider such a situation you'll have to place two sensors and to use their combined signal. To avoid missing part B in the picture below you will need an additional boolean, that tells you whether a part has passed S1 but not yet reached S2.