Sanctaphrax is right, the skill replacement stunt should probably read something like "... when your physical appearance would be a beneficial factor". I've seen a few skill replacement stunts that worked well like that.
The other stunts look good as they are. Though I would rename "Venom", as it implies you have the capacity of injecting a venom into someone you hit. "Adrenaline Rush" or something similar seems more appropriate.
If you are on Google+, I can recommend the Fate Core community there. A lot of people who have done all kinds of conversions yet, all your questions can easily be answered.