Well, I got the right size screws, installed it, and it seems to work fine.
The only problem I'm having is that when the neck and
bridge pickups are both on (i.e., 3-way selector switch in the middle), the sound is EXTREMELY thin, although it gives amazing harmonics. Either I've wired it wrong, or it's just a mismatch of the pickups. The bridge is an Ibanez V8, and the neck is a mega piece of crap, bottom-of-the-line, not even potted in wax, stock Ibanez pickup. I wired in the V8 the same way the pickup I replaced was wired: ground is grounded, and the hot lead that gave the largest DC resistance is connected to the selector switch. The other lead (which I assume gives one coil when used with the ground, since its DC resistance is ~8kOhm, and the other lead was ~16kOhm) is not connected to anything.
I've seen some of Ibanez's wiring diagrams that show one of the hot leads from a humbucker grounded (e.g., the 1994 540R). It seems to me that this would just give you a single coil instead of a humbucker, but I'm sure I'm misunderstanding something about the way this particular humbucker is wired.