A couple of years ago develop something like what you are looking for. It was around an Arduino Nano, using discrete components. Eight arduino pins handle the segments of the display, the current is limited by resistors. The digit switching was done with three arduino pins that are decoded by an IC 74hc238 (3 to 8) connected to an uln2803 transistor array that controls the common cathodes of each of the eight digits. Unfortunately the code I lost. If I rewrite the code I will upload it and let them know.
