Good stuff. Can't wait to see how it turns out!

Now let's get back to the CIS issue. I'd love to control it with MegaSquirt. I recall from an older thread that someone made CIS-Lambda work with a proprietary box, but that wasn't open source and wouldn't even work for CIS-E or CIS-Mot. I'm also unconvinced that it would be fast enough for transients, although steady-state would have to be better. It's too bad that no one seems to have been able to get the CIS-E/Mot differential fuel pressure regulator (DPR) working with MegaSquirt. Maybe I'll make a project of it, but first let's consider an alternative.

While most EFI systems primarily try to regulate fuel pressure and modulate injectors to control fuel flow, CIS generally controls fuel flow by changing fuel line pressure to the injectors. I wonder if this line pressure could be modulated (i.e., turned off and on) to control flow using off-the-shelf MegaSquirt in a non-sequential mode as an alternative to controlling the DPR. The later CIS-E/Mot systems might be physically capable of it (and already have a built-in airflow plate potentiometer), but would probably not be accurate enough due at least to the uneven lengths of the injector lines. Fortunately, "fuel lines may be replaced, relocated" (see 9.1.3.D.1.b), presumably with equal lengths

Also, 9.1.3.D.1.b (final sentence) seems to permit installing "an external fuel pump pressure regulator". Is that different than a fuel pressure regulator (FPR)? Does "an" limit this allowance to one? If the car already has one, can a different one be substituted or added? Could an original one be substituted AND an additional one be added? I don't see any limitations on placement other than that it be external to the fuel pump. I also don't see any limitations to a purely mechanical device, so I think it can be controlled by vacuum and/or electronically.

Are we there yet? Worth a try?