Alright, found it. This is why I don't like Weapon hacks - the code doesn't follow any logic or convention. Anyway, for some reason when the bullet is initialized at around 405879, it's accelleration of 80 seems to get put into [+34], which according to the list should be frame ID but whatever. Further down, at 4059a7 are a bunch of 0a00 things, those are the maximum velocity checks - it'll have to be the same max velocity for all three levels.
I only tested with the level one missle which is controlled by 40589d, though I expect the 80, 40 and 33 above are for level three since it fires three missles that go at different speeds. I'm not sure about level 2, it could be controlled by the same thing as level 1, it may be handled by something entirely different.