Naming King for a boy? Advice and other names?

My SO really wants to name our son King IF we are having a boy. Because our daughters name means queen. I liked the idea but really feel like I wish it was something else with King in the name, so we could call him King for short but he wouldn't have to be called King if he disliked it/ got bullied at school etc. 
I feel like it's a very strong name and if he is anything like his father then King would be bloody perfect lol, but if he isn't then that wouldn't have to be his name..
I'm thinking of making it something like Kingston or Kingsley? But there are a lot of them where we live and my partner wants something different, is there any other names like those with King in the name? 
I love the name Kingsley but my SO really doesn't want that and simply wants King, but I really just feel like some people would think we are all up ourselves or something giving our child the same name as a royal title. Or am I wrong? Is King really such a bad name? 
I'm so stuck! Please help!