The 300 is such a sweet little hercules.
32-spline front and rear output upgrades are out there from JB Conversions
JB also has the 4:1 kit with the thicker,stronger gears
Stak makes its stout aftermarket case
If the 4:1 is to low all-the-time for some, you can swap the lomax gears into the Stak case, then slide a Klune (2.72) Underdrive in front of it and have two diverse low range options to choose from
It'll only set you back a few grand