Thanks Kurt, I didn't realize that - interesting - I knew about the alternators and distributors but didn't realize it applied further..
Guess it makes sense considering what it would take to prepare for one specific engine assembly routine and its necessary parts, verses another - like a grouping of 327 / 215 hp 2 barrel engines to the next which could be 327 / 275 4 barrel variants with different pistons, intake, cam, and carb etc..
Back then it must have been a factory logistical nightmare with so many more options available to customers with often only subtle differences between them, compared to today's limited powertrain choices where everything seems to be lumped into 1 or 2 option packages with almost no variablity...
No wonder often we often hear about mismatched engine components or options from back then.