do you have a proper ground from the battery terminal to the block and from the battery to the rad support?
? grounds for the system are very important. make sure that where ever they bolt to is clean and free of paint and oils/grease.
your voltage regulator for the alt may be bad or again- not a good ground to the case of the voltage regulator to the cowl area.
once all this is up and running can we be sure that other things are working correctly or not.!!
John Mac