Car not charging

It sounds like you have a short somewhere else as well as a probable bad replacement alternator. Being a 1977 you can do an easy test. Remove the ground connection from the battery. Now remove the positive terminal. Next connect a simple test light between the battery positive post and the positive terminal. Reconnect the negative terminal. If you have a large draw the light will come on. Now start pulling the fuses one at a time. When you pull one and the light goes out you have the circuit with the problem. Do not forget to disconnect the alternator to check it and the coil. Being that the OEM system did not have many fuses this should not take long. You will be removing individual feed wires very quickly. Below is a 1976 to 1978 wiring diagram that might help. I would suggest that if you really intend on keeping/driving it has it be rewired with extra fuses. Many melted wires could happen with so few fuses.