Now that I've tinkered with the data a bunch, all I've done is further convince myself that lower is always better
So much better in fact, maybe it's worth the risk of destroying 6th gear on my trans just to put 4.08's in there. It can always be rebuilt
Contrary to my intuition, the gears don't get wider as you step up, they get
narrower when graphed as Horsepower vs Speed. In other words, the higher you are in the gearbox, the less rpm/power drop there is when you upshift again. This is especially true if I can move some of my shifts out into the 6th gear range, because the 5->6 shift is *very* short. Here it is visually:
And again with only the outer two datapoints (less clutter):
Note there are a lot of loose approximations in the data that lead to these graphs (e.g. I didn't have exact-enough dyno figures per-RPM and didn't feel like interpolating, so I stole someone else's dyno graph that had nice grid lines - but the rough shape is all that's important there).