Police 318 Heads

I'm confused, I've been trying to research these and some people say they are just your average 360 heads, some say they are not. I have a stock 318 that needs heads and if these are a good fit I'm interested but if they are just 360 heads I've been told the bigger chambers will lower my combustion ratio and make the car a dog. I just want to make sure what I'm doing makes good sense and not just throwing money away. Do you know what the chamber size is on a shock 318 vs these heads?

Jon