The MAB experiment will be very interesting to me. I am doubtful that you are moving much fuel thru the main jets at 65MPH, and suspect there will not be much of an impact at cruise. It may have a bigger impact on WOT at high RPM though, so you might want someone running shotgun to keep an eye on the AFR if you run it up to redline.
The IFR change from .028 to .031 is a 22% change in area, which is a pretty big jump. Your current results look pretty good though. A change from .028 to .030 is around 15%. At light throttle you could probably run leaner than 14.6 but going to .030 might make too much of a change (you can always add that jet to a future parts order if you want to try it!).
As JimG said, there were 3 changes at once. With the bigger IFR, you may be able to go a little bigger on the IAB. This could help with the 65MPH+ cruise, since I suspect most of your fuel delivery is still from the transition slot. I think you indicated you only had .075, .071, and .067 IABs. Again, if you are really wanting to fine tune it, getting a set of .073 IABs would give you an intermediate step to try.
If your MAB experiment doesn't bear fruit, then you could try the .075 IAB, and if that is too much then time to consider that parts order! It is a little expensive, but I ended up getting a QF IAB jet kit to let me experiment to my hearts content.
