I am not sure where it came from but if it looks factory and you cant figure what Bug it came from it may be from another car that had this engine. The gia and the 914 had higher hp than the bug version. back in the day before jc whitney and every one else sold bug parts its was common to swap for the 53+ hp versions. No one does it anymore since its very cheap to rebuild now with hop up parts. Actually stock parts my be harder to come by.
After market fan shroud was popular in colder climates as well. These make the engines look different but cant tell if that is one since I have not been under a hood of a vw in years.
Sorry i know its not an answer to your question but hope it helps.