You can use the same injectors as anyone else. Cummins invented this neat little copper sleeve that makes the smaller tip injectors work in the heads with the bigger bore. They can be obtained from where ever you choose to buy your injectors.
There are any number of sources where you can get injectors for your engine which were designed to be used in a higher torque, higher rpm, higher HP version of the "B" engine. Basically they work by flowing fuel through them faster, relieving the stress on the little VE pump. The part number I'm familiar with does it so dramatically, that in a non-intercooled engine, I reccommend you turn DOWN the fuel to less than stock. In fact, to prevent smoke, I'd turn down the fuel on any engine, or at least cut the AFC back to decrease the puff of smoke when you push the "go" pedal.
The shop where I work now sets the maximum fuel to mid-spec and dials back the AFC a bit, so it's at the bottom of the spec. This combo results in 1/4 mile terminal speeds comparable to an ISB w/5 or 6 speed and a VanAAken box (not HO or ETH versions). Not as much horsepower or torque, but the 1st gen trucks are lighter and the pump more responsive.
Also, I consider it MANDATORY that you install a pyrometer. This is a dramatic BOMBING modification. Free flowing exhaust and K&N (or other improvements) are pretty much required, and a 16cm2 turbo housing or wastegated 14 or 12 helps too.
Also, it's absolutely imperative that your true engine timing be set, and we've gotten good results from 1. 35. Along with this, verifying the true position of your TDC pin is essential. However, some earlier engines have specs that are higher than that, experimenting would be in order.
Attention: TDR Forum Junkies 
