75-76 Aluminum 833 4 speed Overdrive trans questions ?

I have 2 identical aluminum 75-76 aluminum a body 833, 4 speed transmissions, one complete with factory shifter and rods
1. How much hp/torque will they handle
2 How much with modifications
3. Weak links/poor engineering
4. Availability of parts
5. Reliability/durability
6. Value
7. Requires its own bell housing ?