MAD Industries has provided a nice mod for Go SMS when i asked for help on modding it since it wasnt working right for me. Im using the WP7 font which you can find online. Download that, throw it on your sd card, then scan for fonts and it will show up. Then you have to change it in the settings.
How to use: Go into the settings and select the "iPhone" style/theme and then go change the conversation font color to white.
M.I. Website Here