Came here to mention the spring bars, if you have any 1.2/1.3 spring bars of any type (standard 1.5 spring bar springs are usually too big), it's usually easily enough to pull one apart or cut it open, then just cut the spring to length, done it a couple of times, works perfectly. Drilling shouldn't be at all necessary, after all you can get 1.0 mm spring bars, and no alarm spring is going to be smaller than springs in those.