The problems could be electrical of fuel related.
Electrical - make sure you have good battery cables and the negative is connected to the block and the body with clean connections. If using a stock ECU ignition box, run a ground wire from the ignition box to the engine (prevents ground loop issues in sensing the magnitic pickup pulse.)
Fuel - The real issue here is the fuel sold today vaporizes much easier than fuel sold in the 1970's. Blocking off the intake manifold heat crossover, and running a vapor return line helps prevent vapor lock and boiling the fuel in the carb.