How much gain with lower gears?

Well here's my 2cents
With 3.23s and 25.5s you're gonna hit 100@ 6500 or so in second gear. The shift into third will drag the Rs down to 4500, and 112 will get you up to about 5000 so the engine is just getting back onto the power. This might not be the best situation.
If you expect 112 mph, then you want to trap at an rpm where all the power is just used up. If your power peaks at 4700 or 4800, then 3.23s might be the right gear.
but more typically, if the power peaks at 5400,and the roll-over might be several hundred rpm. So maybe you want to trap at 5800. Still at 112, this would require 3.73s. So now you stand the best chance of getting a low-ET with an engine that makes best power at say 5400 and is able to hit 112mph.
Your engine may vary.
if you have enough power to hit 118, that would be 3.55s.
Or 106 would be 3.91s.
But if your engine power peaks at 5100 and a 5500 rpm shift is appointed, then everything moves down one gear. 118 will now require 3.38s,112s will now require 3.55s, and 106 is 3.73s
All math was done with a 5% slip factor in the TC, so again your results will vary.

But if you had more gears, well, that would require more calcs,lol