Ferrari F1 2018 vs Ford Escort Cosworth 800 CV - Monza 

Not all of them were rally cars, most of them were road cars and could reach just above 150 mph

They weren't just known as rally cars, they were made to be fast at a cheap price.

With mods

It can't. Even with 800hp as stated it was caught almost before the finish line and will be overtaken in the next corner, despite the F1 starting way later, when there was like half a track distance between them. With a GrA rally car and approximately 330hp (which the Cossie was) it would be already overtaken, since it won't have the top speed of this one.