Need advice on setting T-sync on 4 corner idle carb

Isn't there also an idle circuit and transfer slot on the secondaries, even without the four-corner idle? So if setting the idle requires opening the secondaries into the transfer slots, won't that richen the mixture too?

I have an 800 Holley DP with 2-corner idle, and I set all four transfer slots square. This required a 3/32" hole in all four butterflies, but it idles as stably as a 272 @ .050 cam does.