Leg speed is a concern.

I have the opposite problem because my background is being a fixie kid. I was used to running smaller gears and spinning a bunch. My strength is my limiting factor, but my leg speed seems to be slightly above average.

Personally I find it very hard to attack/respond to attacks with a huge gear when doing match sprints. Hit the rollers here and there to work on your leg speed. Keep the upper body still and your core tight. Flying 100's in a small gear will also help a bunch with your leg speed.

Will better leg speed automatically mean a better 200m? I don't think the answer is that simple, unfortunately. I'm leaner/skinnier than most sprinters. Also most of the local sprinters are just straight up stronger than me when it comes to gym numbers. I still qualify very high and race fairly well. Hope this helps