Southern pacific 4449

I restarted a project I had originally started maybe 1.5 years ago, and did a full redesign(first 3 pics are original, last 3 are new) of the wheelsets, I had the nagging feeling I wanted to try air powered instead of motor power(pneumatics with a compressor) and I have an idea of turning 1-2 main drive axles into hidden valve cranks so they are not visible, I just want some tips for making it able to pump both forwards, and backwards, as I’ve never dealt with pneumatics before, I have a...