Did you ever find the belt profile for an 8mm pitch GT2 pulley? I am in search of the same thing. I would like to make some aluminum pulleys for a boat out drive to try different belt ratios. I emailed gates directly and they sent me some of the drawings. I am trying to get them entered in fusion 360 to eventually output to the CNC mill.
Here are somethings I found so far:
https://capolight.wordpress.com/2018.../#comment-5093
https://build-its-inprogress.blogspo...68354574899572