You may actually want to use some injectors that flow rather less than the stock 2.0 injectors, esp. if you're using Megasquirt to drive them. The all-analog D-Jet system appears to have a much easier time than most digital ECUs are varying the pulsewidth by very small increments. So, it can control the idle on even very large injectors, as its "resolution" is really a function of the physical limits of the injector, not the ECU. The Megasquirt system has some difficulty with handling variations in pulsewidth smaller than 0.1ms, and Dave Hunt has already noted he has some difficulty getting idle level fuel set perfectly on a 2.0. The MS resolution simply isn't good enough to injectors that oversized. There is some hi-res code available with 0.000001ms resolution, but that has some other limitations (can't do PWM injector control, useful for low impedance injectors). btw, this is being fixed in the MSv3.0 boards, which should be out this year.
SDS also has a simple flow rate to engine HP table:
SDS Injector Flow TableI'd say something down near 28lbs/hr will be plenty for any Type IV. I believe the 2.0 injectors are up around 36lbs/hr, the 1.7 injectors are around 25lbs/hr, and should be suitable even for a 150hp 2270, let alone an 80hp 1.7, or a 100hp 2.0. The smaller the injectors you use, the easier it will be to control low-load mixture.