If you know what engine RPM you desire at what road speed you can then calculate and decide what gears, tire size, and transmission ratio will get you there.
Try this calculator:
http://www.onlineconversion.com/bigger_tires.htm

I'm not so sure that 4.09 and 4.11 gears in the same vehicle (with same tire size) are a good idea?
Get a few more opinions on that before deciding.
Mud is one thing, but if you plan to use it where you have reasonable traction for both axles it could be a problem.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-