Help identify please: power or manual gearbox?

Yes, a single plane is not the best choice for a streetable combo. A dual plane will make the car more responsive and "drivable". No telling what the cam is. But you may wish to somehow check the P/S unit to make sure it is usable, especially after being "open" like that. It may be less hassle to swap in a manual box rather than get the pump, brackets, pulleys, etc.