You have 192 segments. If you use two of the 74ls154 decoders (one for digits, one for segments) you will only be able to light one segment at a time. That means each LED is lit only 0.52% of the time, max. You also have to do updates at 11,520 segments per second to get a 60 Hz update rate.
You would probably be better off using a 16-bit shift register for segments and the 74ls154 only for the digit drive. Then you can have each digit lit 1/12th of the time (8.3%) and only 720 digits per second to get 60 Hz refresh rate.