So, I finally had time to visit hobby store. Found blue sheet plastic, but was worried about the lamp melting the plastic and distortion due to heat (very thin plastic). Finally settled on dark blue stained glass (3/16" thick or so). I will cut and grind the glass into a circle that fits the lamp bucket in the speedo. I went with blue instead of red to mimic modern hign beam indicator color. I will notify later on how it turned out.

Got it done:
glass filter
speedo completed

Last edited by DavidF; 06/25/2011 2:21 PM.