I also can't get Bushido and it's way too hard to land on a perfect ranking of 1337, 600, 1 etc etc.
Sensei is still possible because you need a rank of under 500.
And Head Hunter (Decap achievement #1) keeps resetting.
And even though I have Disqualified people within 30 frames, I can't get the Cassius Clay achievement. Same for Glass Joe.