Man I am going to nuts on this cuda it needs a different drain plug for the oil has a dorman or something on it sticks out like a sore thumb. Actually looking at NOS ones. Dam never thought the car would go this far!!!!!!
Plain 70’s factory 318 plug work for you? Got one on a dented pan laying in the shop somewhere, also got one in a 72-73ish 440 Truck Pan if that’d work too