The block can warp.
When my head gasket went both heads and both block decks were warped. I was able to get them flat again but be careful with how much material you take off.
Because we use a timing chain, the timing will change very slightly if you take a lot of material off. I took quite a lot of material off (don't have exact measurement but it was a lot) and the timing chain wouldn't match up the alignment markers with the engine at TDC. I just set it to TDC and placed the chain where I knew it needed to be. I had a code afterwards for over advanced timing but couldn't feel/notice any difference. JWT sell adjustable cam gear to fix this.