Just noticed in the config that there is no option to exclude Ocean biome from the generation. Is it possible to add such option or is it a limitation of Minecraft's engine?

Ocean biome as well as the Ice Plains biome don't follow the rules of other biomes when generating. Disabling them would require rewriting a lot of vanilla code, that's why it's not done.

Well, what will happen if I override 0 biome ID with one of biome IDs from the mod? Will it generate the same size as the ocean?

Edit: Seems that I guessed right. But is it safe to do such kind of override?

it will generate the same size a an ocean. but don't worry i'm going to add an option to disable oceans in the next update :)

That's great. Thank you :)