To save someone else the trouble of finding this out the hard way: it seems that FIC manufactures two injector types, one for DSMs, and one for Evos. The difference is subtle: on the Evo injector, the outlet of the injector is a straight tube, which the large lower seals slide onto. On the DSM injectors, there's a flat surface on which the seal rests, and the outlet then dives inward, then expands outward, like a bell outlet. The outermost edge of that outlet is just small enough to fit into the broad opening in a DSM head, but is too large to fit in the slightly smaller Evo opening.
So, I now have a very nice set of DSM 950cc injectors that I'm not sure what to do with. I may hang onto them for initial startup testing with the 2g, since they'll be much easier to dial in initially than the 1600s I already have and plan on running regularly. It was half-tempting to throw the 1600s in the Evo, but they'd be far too much of a hassle to get working properly on something I drive to work every day.