[jray3]

On projects like this I'm not worried about synching up the electronics between engine management and motor control. The engine will behave like it's going downhill. (Just like operating my ICE pusher trailer behind an EV.) The electric rear axle could be completely independently controlled, preferably with a hand throttle, or if off the same accelerator pedal; through a master switch to enable/disable the Warp drive.

However, I think this car will be too difficult mechanically. On any car it is difficult to put one series motor on each rear wheel unless they are offset by using a gearbox, as there's not enough width for two motors, half shafts, and CV joints, let alone at the right angles. Putting a differential beneath a body that wasn't designed for it might be doable if you don't mind a big hole in the floor.
Also, this dual rear motor approach with one per wheel has been oft discussed, but very rarely implemented on a DIY EV. As I recall, the Tropica was then only series-motored 'production car' to do it, and not particularly well at that.
Polychain belts and their cogged pulleys are noisy.

I'd still love to french a motor into the driveline of a pickup one day. That would be much easier.