Well it'll be close from what you can see but from my experience the injector slopes help to an extent. If you add or pull to much fuel it will make you lean or rich everywhere else except the rpm your setting your cruise datalog for. If its saying -3% your adding 3% fuel across the board which will get you we're u want to be at that engine speed to make your ltft 0 but at the same time your adding 3% fuel for idle as well which will richer up your mix because you aren't pulling the same air volume. At the same time you may be going rich on the big end as well. Or lean in both cases.
That's why custom tuning the maf table is rescaled. Gives you fuel or pulls it were it needs be for more accurate tune across the board and better on engine your mpg and performance all the way around. Once that's dialed in then the wot timing adjustment can be done...
And you said something about rear o2s being gone? I hope you have a wideband or other means of fuel readout?
Now I only used the Intune never had a predator so my thought process may be a little off :p