361 Woes

If the smoke smells like gas and not oil, the carb may have developed issues. You could have a bad float. I assume the carb is a Carter 2bbl. Also you may have weak spark from old plug wires.

My suggestion would be to remove the plugs after running the engine at normal operating temp and disconnect one lead to the balast resistor and do a compression test on all 8 cylinders wot. Then at least clean the plugs and reinstall the plugs. Fire off the engine and note the condition of the plugs again.