Lots of stuff can cause rough idle roughness and driveability issues. With any carbureted engine - check all vacuum, mechanical, and electrical systems first.
You mentioned that even after the rebuild - it barely pAssed smog and stalling at lights. Bunch of possibilities:
- Engine problems such as leaky valves, carbon build-up on valves, broken/worn valvetrain
- Ignition problems (bad condenser / points (if applicable), plugs dirty, shorted, worn out or fouled)
- Distributor is shot
- Plug wires bad, mixed up, or crossed (inductive firing)
- Distributor cap cracked or worn out
- Worn rotor
- Bad coil, short in coil
- Ignition timing advanced/retarded too far or way off
- Leaking vacuum or air at carb base plate (bad gasket or warping)
- Vacuum leak somewhere else
- Plugged PCV valve
- Bad or leaking Brake-Booster Diaphram (power brakes)
- Dirt, rust, debris in idle jet
- Carb base warped by installer (too much torque, wrong/incorrect gasket-install problem)
- Carb top badly warped by installer (too much torque, wrong/incorrect gasket-rebuild problem)
- Mixture set too lean
- Idle speed setting too high or low, mismatch with mixture setting
- Float level off
- Excessive exhaust system backpressure
- Throttle position sensor bad or out of adjustment
- Bad O2 sensor
- Leaking fuel pump diaphram
- Inconsistent fuel pressure
- Charcoal cannister defective or saturated with gas
Road trip should have washed down any dirt left over from the rebuild. Look at teh exhaust and see if it is running rich or not (black smoke). That will get you started in the right direction. If you can't tell - you can look at the smog results:
Normal CO with High HC - points to ignition related problems
Low CO with High HC - points to vacuum leaks
High CO with High HC - points to carb problems
Though you could a combination of problems there.
Good Luck.
