Replacement 68 340 four speed cams

I have a question here, from what I can find out the 340 4 speed cam isn't much bigger than a automatic 340 cam. .015" on the intake .009" on the exhaust, 8* more duration on both the intake and exhaust, with 6* less duration at.0.050" for the intake and exhaust. And by using a ivc calculator it would have to have a 116* lsa to get ivc at 70*. If this is true, then I don't understand how the 340 4 speed cam is a more aggressive cam.