M-Code Cuda barn find

Hummm , I assume the vin is a N right? Why would the engine be blue? Also left side m code engine mount doesn’t look correct to me..is it? Too high… looks like 383 mount.
Engine is orange, the valve covers were taken so later model covers were put on to keep the rodents out. M-Code, not N. Engine mount is correct, the engine has never been out of the car...