""All that said, I thought you were a proponent of using the float level to fine tune the AFR via external means. That sounds like a good idea to me, particularly on the secondaries. Are you concerned that does not give enough adjustability?
""

I do like to use the floats as an external fine tune, but my rear float is already at the halfway mark. At that level, I know that I can get +/- .2 but I am not sure about taking it up higher than that mark. I think that I need a few ticks richer before I can be comfortable with that float height.
I might try the smaller rear HSAB just to see and report back. I know for a fact that making this same HSAB swap on the primary side changes the A/F a bunch. But as you wrote, the seconds are not active at this rpm level but I am not sure that if there is any residual affects on the main circuit.

Thank you for the reply. That explains it very well.