Wrong heads on motor?

[Dad's72]

I need help. I'm cleaning up the motor that I just bought from a buddy that he thought was a crate motor. At first glance I can tell that the head on the driver side of the motor is way shorter than the head on the passenger side of the motor. Has anyone ever seen anything like this? I'm going to try to take the valve covers off so I can see the casting numbers. I found a metal tag that shows its an AC Delco remanufactured motor for GM. But it was assembled in Mexico. I guess the build sheet wasn't in Spanish. This is my first build anf first time trying something like this. I'm pretty mechanically inclined but I can tell that this isn't the right head for this motor. Am I screwed? I may have to ask that money for my money back.