It is worth noting that a 4.88 gear set in 5th will behave like your 4.10 gears do in 4th. (AX5 has a 0.85 overdrive). Since the switch to 4.88 gears would essentially be the same as losing your current overdrive, perhaps your efforts would be better focused on upgrading your transmission to one with a lower first gear?
Drive around without 5th gear for a while, if you are happy with the mpg and performance, maybe you should consider swapping in an NP435 or SM465, they are readily available, cheap, bullet proof, offer a mild to wild first gear, and you get rid of the weakest link in your current setup (The AX5).
Novak adaptors is my favorite site for laying out all the parts your conversion will need. Gear Ratio Calculator
will show you the ratio breakdown for your current setup vs. what you could swap in.