360 casting

I have no idea if the heads are original to the block or not, guess I'll find out when it all comes out. It's currently in a mid-'60s C Body so it's kind of a mongrel already. It's getting swapped out for a big block. The person who owns it now has had the car 4 years. He was told by the previous owner it was a 318 so he just presumed all along it was and never bothered to check. I just happened to look up and see the driver's side casting number and realized it was not in fact a 318. It's got a baaaaad knock so hopefully the block is savable.