Electronic Ignition Connection

Yes, you can. BTW, it appears 67Dart273 misread and thinks you are installing a newer-style Vreg and newer "isolated field" alternator.

The old-style Vreg uses "high-side switching" with the low-side grounded (one field brush). If your alternator has two isolated brushes (all square-backs), ground one of them. Your harness is for the later-style Vreg which uses "low-side switching". Those ran switched +12 V (blue) to one field brush and Vreg controlled the other brush (grn, low side). I would leave both wires in the run to the alternator to allow changing to the later system someday. I also wouldn't snip off the triangle connector, instead I would see if bullet connectors will fit tight in the holes.

Connect the blue wire to BAT terminal of Vreg, connect the grn wire to FLD terminal. The 3rd Vreg connection is the case to ground. The factory relied on the sheet-metal mounting screws, but smart to run a dedicated jumper. At the alternator side, don't use the blue wire, but isolate it since hot in key "run". Connect the grn wire to one field terminal. Insure the other field terminal is grounded to the alternator case. Some later square-backs have a ground stud on the case.

The ballast resistor has nothing to do with the charging system, and is only for the ignition system. They simply tapped 12 V switched power (IGN) at the resistor terminal (upstream side) for use by Vreg (both sensing and for power). Insure that both get that IGN power in your harness.