Airspeed Indicator Re-Screen

[George O'Connor]

I am replacing my panel in my 63 PA-30 and want to re-screen the airspeed indicator. I have often wondered why there are no blue or red lines on the indicator. I wanted de-clutter it a bit and revove the knots on the inside and add the red and blue line. Just wondering if this is legal to do. The shop says I can screen ot anyway I want. Input is appreciated.