Haven't heard of any Z270 mobos being used for Skylake non-k OC. I wouldn't really recommend going with non-k OC, but if you're determined to I'd go with a Z170 mobo, although that's not guaranteed to work either. What CPU are you planning to get?
Be careful choosing a Z270 with a 6-series CPU. Not all of them work out of the box with a Skylake and require a 7-series chip to boot with and update the BIOS to accept it. Some newer made Z270s come with the updated BIOS revision to accept Skylake. I don't know which ones.
200 series mobos support Skylake out of the box. It's only running Kaby Lake on 100 series mobos that may require a BIOS update.