here is the website that proves your statement as incorrect, Ford will even sell you a track ready mustang if you want it.
Are any of these engines used in NASCAR, F1 or any professional autosports? If not, they are not “racing engines”.
By the way, for very low volume parts, it would make sense to make them by hand, so just because Ford lists them does not mean that they are made on an factory assembly line. That is if they are actual engines used in professional autosports. If they are hot rod engines, a factory production line would make sense since those have a bigger market.