It wouldn't be too hard if you were just draw one up as solid pieces. Like the entire block is one part, head another, valve cover, oil pan ect. without any real detail in actual function of the engine. More just for building a chassis around for example.
Getting into rotating assemblies, valve train, oil and cooling passages would be the time consuming and difficult part.
I thought about how great it'd be to grab those when I worked there. Then I weighed the cons (being fired, lawsuit, money, jail time, etc...) and decided not to. ;-)
If you come across some, please share though.