its nice to see someone attempting to reuse a prius synergy inverter.
im waiting for the inverters to go down in price on ebay, before i grab one to tinker with. theere's many of them for sale, but the idiot sellers dont realise that no one changes a faulty inverter, since its bullet proof, and most times, covered by waranty. very soon, ebay will be flooded with this inverters from wrecked priuses,
i dont mean to bust your bubble but that inverter is not "intelligent". cannot operate by its own, it still needs the main ecu to control the boost converter, mg1, and mg2.
this guy tore one down: http://techno-fandom.org/~hobbit/cars/ginv/
from your post, seems that you have already figured that out. looking forward to your conversion, and success.