Well, that's not optimal.
I put a scope on the fuel injector signal from the logic module to the 12-button EVIC in my 1984 Daytona Turbo Z. Turns out, the signal varies in duty cycle at idle, but is generally 60 ms on, 80 ms off, approximately.
The amplitude is only 0.4 volts.
In my 93 Daytona, the data is passed through a serial bus from the body control module. The only place I can pick up the fuel injector signal is at the injector itself (or at the other end of the wire, at the PCM). The amplitude there will be 12 volts, since it switches from a 12V power feed to ground.
So unless I can think of an easy, clever way to scale the pulse down to a 0.4 volt amplitude to feed the EVIC, I won't be able to install it in the '93. Or at least, not have use of the instantaneous mpg reading, and perhaps not the average mpg reading (the latter depends on whether it uses the fuel gauge reading exclusively, or a combination of that and the EFI signal).
Then there's still the problem of how and where to stuff the EVIC into the dash - either in the center stack, or behind the Daytona trim strip across the top of the dash, from center to passenger side.