That's correct. But, as it turns out, only in theory unfortunately. As the others have stated (except for bmc), the numbers were all over the place in the early years. By the time his '76 was built though, things seemed to be a bit more normalized and were a bit more consistent. I bet they were still not perfect though.
My '71 barely has (if I remember now) about 1.2° positive on one side, with about .8° positive on the other, with 3.5" of lift and 7° bushings.
All that means is that it didn't have the specified caster to begin with. The bushings are correcting for the lift, but the caster was starting out with a deficit.
So, "by the book" (and if your caster was what it was supposed to be from the factory in the first place), then the 4° bushings would be fine. But in practice, you pretty much have to have your alignment specs checked BEFORE the lift, so you know what bushings you're going to need.
And then hope that you are starting from a good point.
There are certainly plenty here with normal caster readings after bushings, but more often than not, they've not been enough to correct what was wrong to begin with.
I had a friend who actually returned his '72 or '73 Baja Bronco back to the dealer(!!!!) as a lemon because it could not be correctly aligned with the normal methods. And it was "stock", for a Baja.
Both his caster and camber were so far out of spec that he couldn't get any miles on his tires before they started showing noticeable wear patterns.
Yeah, a Baja got returned to a dealer. Geez. If he'd only known what we know now, it would never have gotten to that point. But it did. Bummer.
I think that was even before the "Lemon Law" was thought of, but he complained so bitterly, and was so persuasive (and probably was a good regular customer of the dealer) that they took it back and either gave him his money back, or another one (not a Baja though) in trade. I can't remember which way it was resolved, but it got returned.
Paul