It depends on which 2.0L harness you use. The 73-74 FI set-up is different that the 1975-76 setup. Intermixing sensors, injectors and other parts spells trouble.
If you mount the 2.0L harness using the 1.7L air plenum, the 2.0L harness fits sort of, this from a trustworthy source:
"I tested fitted the harness tonight. Everything fits except for the TS1 wire, as shown in the photo. The TPS lies directly under the throttle body (where the big black elbow connects to). Because the TPS is so far towards cyl 1 and 2, the TS1 wire is too short to reach the TS1 sensor, which is located on the airbox directly opposite the throttle body. (Lower left of the 2nd image.) To resolve this, I propose leaving the TS2 length about the same, but branching it off separately from the TPS wire. The wire will leave the harness a little “late” (past the sensor and loop back) but it should fit. Moving the main TPS/TS2 branch to towards the ECU about 4 inches would help even more."
If you transplant the entire 2.0L system, incl the airbox, throttle body, you'll get too much air into the engine. and you need to modify the intake runner mounts and the TPS connector, maybe more.
Why not just correctly fix your 1.7L set-up - get a new 1.7L harness?