200 Butterfly Strategy advice?

I signed up for the 200 fly next Sunday and am wondering if anyone has some advice on how to swim this. My twin brother told me he swam it in college, and by the last length, he felt he was actually moving backwards. I'd like to avoid that if at all possible. To get into shape for this, I've been doing a lot of 25's fly with 10-15 seconds rest. I started doing 8 at a time and have worked my way up to 40. Yesterday, I did 20 x 25s then 10 x 50 on a minute. Questions: Pacing--reason would say to go out slow so you have something left for the second hundred, but I wonder if this is right. After all, you get tired either way, so maybe going out reasonably fast means you will end up with a better time (albeit a greater feeling of misery on the last length or two.) I'm not talking a sprint pace, but a reasonably fast clip. Or is this a recipe for disaster? Stroke mechanics--does the fly need to be modified for a 200--i.e., not pulling all the way through, gliding longer, hand entry a bit wider than usual, etc. I've read that some people can swim a continuous mile butterfly, and I wonder if they are swimming the same stroke I do. It's hard to imagine... I have only swum the 200 fly once--last year--and got a 2:30 on it. My 100 fly has improved this year (a 59.59 , the first time I've broken a minute since high school 31 years ago), and I am in better overall shape this year, so I am hoping to lower the 2:30 to at least a 2:25 (which would give me the Y age group record in our league.) Any advice from 200 flier veterans would be truly appeciated. Thanks in advance for your words of wisdom.