With a 45@28, you will probably be looking at closer to 2# per inch instead of 3. That can vary with the bow though. My 60@28 longbow only gains 2.5# per inch, and lighter weigh models have gained around 2.

Personally, I like a heavier, slower arrow vs. a lighter, faster one. Speed doesn't kill, penetration does. Speed is only effective if the arrow maintains momentum. Lighter arrows loose momentum faster on impact.

If you shorten your shafts, you will have to go up in point weight to get good arrow flight. If you are pulling at least 40#, and that weight is legal in your state, I'd stick with it.

Chad