Here are the parts I ordered from Aliexpress:
in 30 tooth, 6mm width, and 8mm bore (for the c-beam)
(you could probably also do a 20 tooth for a faster 3:1 ratio, which I bought but didn’t use)
in 60 tooth, 6mm width, 6.35mm bore (you might want a 6mm bore, but the 6.35 worked for me, and allowed a little play to aid in getting the belt on. Also, I had to replace the set screw on this one since the one that came with it was too short to let me tighten it up enough to not slip. I will try to remember to update with the screw size when I get home, but I think that it is an m4)
200mm length
200mm length of travel, 8mm lead
I used one of the original L brackets from the z-axis kit and a piece of aluminum sheet to provide connection to the c-channel. I can get more pictures if you like once I am home.