Thanks for the quick answer. I'm truly up in the air on how to carb this motor. I know some guys have had luck with the 390 Holley 4 barrel on similar sized sixes but I haven't seen a ton of people on this site using them or the AFB probably because of over carbureting the motor. I like the idea of a 2 or 4 barrel rather than running a multi-carb setup. I was figuring the AFB would run around a little under half its CFM rating before the secondaries start to open due to the smaller primaries, but I might yield to your real world experience. Any other tips or tricks that come to building a warmed up 261 would be much appreciated.