Did a little research, it sounds like 4-hole spray (which is a disc-type I think) is the way to go:
"5. Valve design
There are three basic valve designs used with variations on each: pintle, disk, and ball.
The pintle-type valve is the earliest design but still popular. And it is the design used on our cars. The solenoid lifts the pintle out of an orifice to release fuel. For our DOHC models, there is an additional orifice with a "figure 8" design, as can be seen on my web page 2-inj360.htm. The pintle is also visible. The problems with the pintle design include increased chance of clogging in the small orifice area, slower response time because of heavier armatures used to lift the pintle, and reduced service life.
The ball-type injector uses a ball (actually half a sphere) to seal the metering orifice, rather than a pintle. This allows the use of a lighter armature and so response time is faster than for pintle types. There is also less wear for a longer service life. The orifice can be designed with multiple openings for a wider spray pattern plus more fuel can be delivered for a given drive time.
The disk-type injector eliminates the armature and the solenoid acts directly on the flat disk through the core of the injector body. The flat disk rests on a seat that has an orifice in it. This arrangement is even lighter than the ball-type for an even faster response time. This disk and seat design also results in less deposit build up at the orifice and longer service life.
If upgrading our injectors, the turbo owners should consider ball or disk type injectors because the faster response time of the injector (over the pintle style) should partially offset the lack of peak-hold circuitry in our setup."
(yea it's a Dodge Stealth site, but injectors are injectors.)
Peak-hold circuitry is for low-impedance injectors(which have faster response time), if anyone is wondering. The Mustang EEC-IV and EEC-V use high-impedance injectors. This could explain why those #42s are 4-hole. That kind of flow rate probably works best with a faster response time.