There's a ton of threads asking this question, so I figured since i've been through it i'd clarify things.

Yes, an LS distributor will work on a B16. You have to saw an ear off as seen here. When bolting to the motor, not all three bolts can be used obviously. The one on the left is a from a B16, right is LS with the ear sawed off.

I've ran these both and they both work fine, however, I began with the LS and eventually bought the B16 because oil leaks out around the hole where the distributor goes in because not all the bolts are used. The oil leakage is shown in these next two pictures, the first of the distributor, the second where you can see a small puddle of oil in the hole.



So, if you need a distributor for your B16 and have the money, get the B16 one because it is obviously the one made for it. If you're short on money or have an old LS dizzy lying around it is usable and will work fine, but be prepared for the small leak.