About that over-gearing thing...
I keep seeing that over and over on these posts.
A couple of points to remember...
Ford used a 4.10 gear STOCK on the Ranger pickup with 28 inch tires.
Many auto manufacturers used a 4.10 gear set in the rear of their street cars, often running 25-26 inch tires -- with no overdrive.
4.56 with 33s is spot on - just around 200 rpm over a stock setup with 3.73 gears and 28 inch tires.
Like I said above -- I'm running 4.10s with 33s and WISH I had the 4.56 gears!
My kiddo was running his Jeep XJ with 4.56 and 33s and it runs right next to mine -- only better. (He's now running 5.13s with 36s, and I'll be running 5.13s with 38s on the Ranger I'm building, but with a doubler t-case for better low end).
You will not be over-geared.
Now, 6.72s with a 33 tire -- that's over-geared! (the ratio in rockwells)
Here is a quick chart that I often use to figure out gear ratios with tire sizes. The chart is setup to indicate RPM @ 65 mph with NO overdrive, so factor in your overdrive (typically .25, so multiply the RPM number by .25) for final RPM.
Color code:
White -- out of possible RPM range
Green -- lower than stock RPM - economy gear - not for off-road or tow
Black -- stock RPM range - daily driver - all purpose, factory gear
Blue -- Higher than stock RPM - performance and power - off-road and tow