inline 6 cylinder help?

i was given an inline six cylinder from a friend of mine i found the id numbers but dont know anything about the engine. i would like to know the year, model, and specs about the engine? I was told it came out of a 1968 chevelle but not for sure, any help would be greatly appreciated. the block numbers are 3921968, thank you for your time.

Well, the block casting # 3921968 is for Chevrolet/Olds 64-76 230-250