Dave,
I have not watched the AFR while power braking to witness a lean condition. The only lean condition that I have right now is when I am cruising and I very slowly get into the throttle for a few seconds (before the seconds kick in). Then I see the AF going into the high 15's during this situation. I was lean into the 16's until I raised my front jets up by two and then it richened up slightley. I am going to see if the .033" IFR's helped with this issue. If not, then I will bring up the main jets by another 2 sizes.
My A/F gets rich quick when I drop down the HSAB's. The .039's work great on mine. My cruising A/F is always in the 13.8-14.4 range with .062 main jets, .060" IAB's, and I just recently changed the IFR's from .031 to .033's. My WOT numbers are in the high 12's and I am working on bringing that down to the 12.5-.6 range.

""My cruise is ugly rich, so I don't want to raise the IFRs, and am also reluctant to drop the HSABs (current .035).""

I have been tweaking my cruise A/F with my IAB's and my front float level. Since my HSAB's are leaner with the .039's, and my main jets are leaner with the 62's, I am using .060" IAB's to keep my cruise A/F as mentioned above. I also had to go richer on my PVCR's to .071 to help out on the acceleration.
If you go with the .035/.033" HSAB's, can you lean out your cruise with leaner IAB's?