I was thinking short block in my earlier post as that has been ruled to be considered "engine parts".
The long block could be argued is essentially a complete engine as it would be mostly complete. You still shouldn't have had a problem with just the long block as it was a direct replacement for a ceritified EPA engine. Were they saying "prove it"? I thought your problem was you had to jump hoops to import it as a business from our previous brief conversation. Stop citing the CFR to your Customs agents and they'll lay off you...
Do you mean the blank form or the completed one? I already posted the blank one. His compliance people will more than likely not be in the habit of passing out Entry documents to people to solve Internet forum quarrels. Especially since this guy sounds like a CS rep.
On average, you've got 5years from import to worry about CBP catching up on paperwork review after the goods are released and seeking additional information like PT mentions above. Read this to see what an extreme instance of skirting the laws can be.
http://wot.motortrend.com/feds-begin-to-seize-illegal-nissan-skyline-gtrs-in-california-6257.html#axzz2LOYKAyYw
As a licensed Customs Broker I would say noone should try and fraudulently complete forms in order to get around import regulations as there are hefty repercussions if you are found out. Jail time is unlikely but fines/forfeitures are very real. There are loopholes and grey areas but those need to be discussed on an individual basis with someone familiar with import law. As an individual, ignorance of law wont allow a free pass with CBP and they'll make you return it or forfeit it for destruction if it is caught. They used to let things slide for personal use but not anymore.