Had to drop by and see what you are doing. I used a w mart fixie. Its the common double diamond frame just what the CG was designed to fit. If you have an 18t fixed sprocket on a flip hub the common CG 9 hole sprocket will bolt perfectly to it.
The bike I built is the one with the 3spd fixie hub as a trans. Started as a 700c I dropped it to 26".