Cryo treating blocks?

Well and that's what I thought, I figured it had to have been around for quite a while and I had heard of rockers and lifters being cryo treated but never had heard of an actual block being treated. My goal is only 600ish hp out of my W9 360 but I'm planning on doing as much overruling as possible to ensure it lives. A fellow mopar friend of mine has had a 360 magnum survive at 625 hp + 250 shot on it. No hard fill either. And people have advised against things such as girdles, 4 bolt main caps even when not using the outer bolt holes etc. So was looking into this