Gear ratio and tire size 833 4 speed
Manual-trans cars usually got 10% more gear to compensate for the loss of TM(Torque-Multiplication), that goes on inside the torque-convertor, mostly in first gear.
I gave you a like, lol.
Taking in account, when I looked up my cam, it was recommended for 3.55 gears. And best between 2500 and 5800 rpm
Those numbers are somewhat arbitrary. Compression ratio, cylinder pressure, and cam timing will all affect the numbers, as will the induction system, as will the engine's bore and stroke.
The cam's actual powerband will be about 1500rpm from the power peak to the torque-peak. However, some combos will carry the power at say 95% of peak for several hundreds of rpms. Similarly, a lot of cylinder pressure will extend the lower limit even more hundreds of rpms.
But, yaknow, a crappy combo can destroy your expectations pretty quickly.
What's a crappy combo?
Well that's opinion, and so;
the one that tops my list is
an 8.0Scr 318LA with a 340 cam and big ol' open-chamber big-valve heads, with log manifolds, lol.
Been there/done that/never will again.
If I may; remember this, the lack of gear only hurts at rpms where your engine is down on power. So this equates primarily to starting off from zero mph. But it repeats at regular intervals in each gear, whenever the rpm drops into the soft zone. If that happens in a particular speed zone, that you enjoy being in, that's when it really hurts.
As someone mentioned, on your chart, 3.91s and 2.76s are pretty much the same bunch of gears except offset by one gear.
If your favorite speed-window is 35 to 50 mph, and your engine makes peak torque around 4400 rpm then the Road-gear of choice might be 10.41 which gets you 4370@35, and 6240 @50mph. So then you have no choice but the 3.91s because it is the only gear that has the 10.41 ratio available.
But I gotta tell ya, if your engine lights up the tires with 3.91s, you are going nowhere fast.
So then you got a choice; to fix the traction issues, or to swap to a lessor and lessor gear until you get under the excess power.
What I mean is this, suppose you are in a shallow sweeper, in first gear, and you step on it just a lil too hard, and the tires spin. Now you are sliding and in imminent danger of wiping out. It might be better to re-gear your car into a different lower rpm, where there is less likelihood of busting the tires loose when yur not wanting them to.
Yakno, people laugh at 2.76s in a performance car, but guess what; First gear with 2.76s, will get you to almost the exact same place as Second with 3.91s will; namely 65mph at ~5800. The engine does not care which ratio goes where, it is only subject to the combination of the two, which in this case is from 7.34 to 7.50.
Obviously two gears has the potential to get there quicker than one gear, unless it spins all thru First gear, lol. But, but, how much quicker? Either gear will get to 60mph in under 6 seconds with a half-way decent engine. Maybe 5.5 seconds. Is it worth it to you to sacrifice the lower cruise rpm to use the ever so slightly quicker 3.91s? Only you can answer that.
I suppose this is why 3.23s are so popular, they are about half way in between the 2.76s and the 3.91s.