Living with 3.91's
A 30% gear change is sortof like just using the next gear in the trans.
For instance; Say you had 2.76s and went to 3.91s, the road gears with a 727 are
------ 6.76-4.00-
2.76 versus
9.58- 5.67-
3.91, ---- So you are just trading one gear for another.
IMO,
what you should really do is get rid of the 2400 stall and swap in something like a 3200.
Say at 2400 your 360 was making 300 footpounds, and saddled by 2.76s, the take-off torque is 300 x 6.76 = 2028 footpounds. But
say at 3200 your 360 is making 360 ftlbs, which is then 2433 ftlbs. Which is
20% better. That would take 2.76 plus 20%= 3.31s to equal the 2.76 at 2400.
Now, you can go up half a gear say from 3.23s to 3.73s
Hpwever
This does not take into account, convertor efficiency.
Say your 2400 has an slip-ratio of 1.6, making your 6.76 to be 10.81, but
Say your 3200 has a ratio of 1.9 making it 12.84, which is a further increase of
18.8%, now your roadgear is up 1.20 x 1.188= plus 23.76% .....
All without changing the rear ratio.
If it all goes up in tiresmoke on the starting line, maybe you lose .4 second in the quarter. But not geared right at the traps is not gonna cost you the same amount of time, unless maybe a shift gets in the way. Lots of guys find out that more gear at the traps may not translate to more speed nor a lower ET.
Just like to know what it is like living with these gears on the street
To answer your question, on the street , it hardly matters cuz
a 360 is gonna blow the tires off,
in first gear, pretty much with any 3series gears anyway.
and Second is gonna get you to way past the speed limit even with 4.10s
On the street, I want Second gear to be my home. I don't want tirespin at WOT at 30/35 mph. and I want the engine to power-peak at around 50/55mph. I will gladly run down the backside of the power curve, all the way to 60/65 in Second gear.
Thus my gear of choice for a 268/110 cam is gonna be about 4.30s, for 5500= 62mph. Thus 2750 will be about 31mph, in Second gear. Thus, this is about as fun as it gets on the street, with an automatic...... and said 268 cam.
But I gotta tell ya, a well built 360 will blow the tires off all the way thru Second gear, with 4.30s. and what this means is; why the heck did you choose a 360, lol, if you can't run to 60 mph with the throttle WFO, without tirespin. Tirespin will get you into trouble real quick.
You could have picked a smaller engine and/or a smaller cam, and/or a smaller carb, and got there very nearly in the same amount of time, without all the tiresmoke............ 4.30s are a game-changer.
I yanked them out and sold them.
I can do the same with less. and not pay the fuel-economy penalty.