Okay, I give up trying to find main jets for the secondary carb. So I rolled my own. Assuming this photo uploads: the one on the left has the right outside dimensions (8mm, 1mm pitch) but way-wrong bore. Second one has 5x0.8 thread, and I seem to have a million of these lying around. Drilled/tapped to put them together (3rd jet, after running through the 8x1 die). The 4th jet is what it's supposed to look like.
Yeah kinda crude, but I just used hand tools. And it works, dammit.