Lee, You are correct that stamped date on the front is the actual assembly date. Up until about 20 years ago there was no crate engine program. Engines were sold via the assembly plants. I am convinced that motors were ordered in batches and sent by sea to Modena.
Only item I am very intrigued about is the carburetor (mine is long gone, replaced by a holley) The build sheets I have seen list the carb as an Autolite 4100 series C6ZF-C again I doubt it to be accurate as C6's may not have been around still, but who knows, I guess we should contact Dave Catagallo maybe he would know if the archives still have copies. I know who would have the info but then it would cost a lot to find out