How do you intend to use the truck? Daily driver? Mud bogs? You gonna take it up the Rubicon?
When you request options that “will hold up” it leaves room for interpretation.
I don’t know of any 4 or 5 speed available that will be as simple or tough as the 465/205 combo you have.
I ran the “weak” 5 speed getrag 1500 (aka HM290) for a few years in my k10 and it held up fine for general daily driving including some basic off-roading and Sierra Nevada snowstorms.
The NV4500
@Strick recommended or even the NV3500 are both decent.
All of the modern options will require conversion to hydraulic clutch cylinders, moving the cross member, a 208/241 TC, appropriate shifters, moving the holes in the doghouse for shifters, and changing both drive shaft lengths.
Automatic transmission swap is a whole other set of tasks but may be a viable option.