Automatic..................

Ford C4 is popular with drag racers
On manuals the Dog Gear needs to mesh with selected "gear" and also slide from 1st to 2nd so that all takes time
Not sure removing "teeth" from the Dog Gears would help anything, either they line up and engage or they don't line up
Assuming 4.0l transmission
The 3.40 1st gear ratio to the 2.05 2nd gear ratio means larger RPM change(drop) is needed for input shaft to match output shaft when shifting from 1st to 2nd, and that takes time.
Good clutch disconnect and good pilot bearing means input shaft can be slowed down faster to RPM match "gear" and Dog gear
You could look at/for transmissions with closer ratios, not sure they make closer ratio gear sets for the M5OD-R1.
Doesn't sound like you need Over Drive, lol
It looks like they do make a closer ratio for the M5OD-R1, used in the 3.0l and 4cyl models
3.0l trans is 3.72 / 2.20 / 1.50 / 1.00 / 0.79
4.0l trans is 3.40 / 2.05 / 1.31 / 1.00 / 0.79
So you could put the 3.0l gear set in the 4.0l trans
This would mean closer RPMs so faster RPM matching
They do say synthetic transmission oil makes for faster shifting, but just passing on anecdotal stories, don't know that first hand.