This seems like an awful lot of discussion over a this scenario.

It has been known for a long time that when running a 84.5 + bore on a FI B-Series motor - there is a chance that you will have problems with your headgasket sealing.

It's not worth the hasstle. . . what good is an extra 10 HP from an excessive bore when you have to dial back boost to keep from blowing headgaskets?

I know it sucks to re-sleeve a block, but that's life man.