Small Block Mopar Engine Date Code 3-4-66

I don't believe it is a poly block based on the heads. It may in fact be a 273. I will go back and look at the freeze plug location. There is no numbers stamped on the drivers head seam. Block is clean and does not have a lot of grime on it. I have been told it has never been opened up except for the intake changeover. I'm betting it's an early 273 block based on the info provided by Pishta. Thank You for the help. Is it worth $200.00?