Found a used pull out set of 4.11 gears (front and back) for sale locally for a really good price. Always considered to step up to 4.30s to help maintain the rpm band a lttle higher on the interstate. Would it be worth the step to 4.11s from 3.73s?
I put 430's in my 7.3 6spd and in retrospect it did just fine what I did w/ 3.73s it and 35's.
I found that 35's and 430s' wound it up a bit too much for hwy as I like to do 5-10 over. 80mph w/ 430s killed my mileage down to 15-16 IIRC.
Before the swap I was getting 18-19 at the same speed.
If you're pulling a trailer you might benefit but even w/ my current setup I pulled around 10k from S. TX up to NE and even stock tuned it ran fine. Using the tow tune was a really big leap.
Just my experience but I'm trying to figure out why you want rpms for the hwy??
good luck