DOHC question

Just a quick question. Whats the differences in the MarkVIII DOHC and the one in the cobra? Based on my readings they have a different intake, and the MarkVIII has a cast crank..... is that the only diff? what if I put a cobra intake on it, will the crank still hold up to those high rpms? The reason I am asking is that i found one really cheap so i am considering a swap



Thanks