The engine shown in the picture is a Pontiac V8. The way the coolant crossover pulls up to the water pump housing is very distinctive. The problem is that there's no way to tell what displacement it is, since Pontiac V8s all look the same from that angle. It could be anything from a 265 up through a 455. I'm not certain you could tell if it was a 301 from that angle, since I've never owned one. You need to check all the stamps, casting numbers, and look for the displacement size that's cast into the block on the driver's side underneath towards the front. That will tell you what it started out being -- but it could also have been bored and stroked so there's no way to actually tell unless you disassemble it. In most cases just establishing what it was originally is close enough, though.
