That's a perfectly cromulent set of goals.
My concern with the plan is with getting a poorly maintained donor. It would have bad wheel bearings, &etc.
And using a transmission. I ran the numbers in a thread somewhere, but by using a single-speed polyphase DC drivetrain, I had a budget of 450lb for batteries without exceeding the Beetle's stock weight; IOW by removing 550lbs of weight.
Compare fabricating an adapter to mount the motor to the Insight transaxle to adapting Honda and Toyota axle shafts.