Hello arklan and welcome to the forum.
That's going to be a great project! It'll be pretty ambitious for the reasons you mention - trying to figure out how to make it work with all the sensors, controllers, etcetera.
This reminds me of Mitsubishi's i-Miev. I wonder if that vehicle could be any sort of a guide as to how to approach doing this? I also wonder if Mitsubishi would ever replace these two platforms with one platform that would serve both forms of propulsion - internal combustion engine & electric? Other manufacturers have taken this route.
I'm definitely interested in your progress with this and look forward to reading more.
View my fuel log 2015 Mirage ES 1.2 manual: 50.1 mpg (US) ... 21.3 km/L ... 4.7 L/100 km ... 60.1 mpg (Imp)