1966 Chevrolet Impala 427 non SS questions

[garycharlton1960]

Hi everyone. I have been asking questions on the Yenko site to get information and some understanding on some cars I am going to be selling for my boss and good friend who recently passed away.
This was his 1966 Chevrolet Impala w/ factory 427 cu. ci. and it is not an SS. I have read that the SS was not a performance package but that it was just a trim package. I have heard from several people that this car is rare because it has the 427 and is not an SS car. The numbers show it to be a v8. The engine appears to be untouched and seems to have the correct brackets and hardware and the hose brackets seem correct. Is there a way to verify that the car did in fact come with the 427 engine? I included a photo of the tachometer. I would think the red line would help in determining the engine. Thanks, Gary C.