I have struggled to find a comparable striker. I was going in with the idea that a gun fighter is a gun fighter regardless of style. Haven't really found an example.
Having said that striking styles are less likely to match people up like that.
Yeah, you can have absolute divisions in grappling tournaments without so much danger of someone getting seriously hurt. If you want to see that sort of mismatch in striking you have to look to the early days of MMA, before they instituted weight classes. Keith Hackney vs Emmanuel Yarborough is an example of a striker beating a much larger opponent.