How can I Animate from stroke to fill to give the effect of a light bulb changing from dim to bright?

[Gast]

I need to animate the following images from the stroke glow text to fill glow text and from fill to stroke. I believe there should be several ways that this can be done, but I would like to create the effect of a light bulb going from dim to bright (as I am using glow and stroke effects in the images below, possibly giving the fill a higher glow radius) when animating from stroke to fill and vice-versa for the opposite. How can this be done?

[Dave_LaRonde]

Duplicate the text layer.  Make the bottom one fill only, and the top one stroke only.  Animate the opacity of the bottom layer.  I figure two frames from 0% to 100% opacity.