Yes to all of the above..except a big NO to what your "expert mechanics" have suggested.

A 1200 fuel tank was designed for a "mouthful /minute" fuel delivery. There is minimal baffles and because there's no return line on 1200s. there is no swirl pot in the tank.

EFI systems are completely different, The fuel rail needs a lot of petrol thrown at it, most of it goes back to the tank via the return line, this should go to the swirl pot in the tank, or to the surge tank.

1 low pressure pump and 1 high pressure pump is required.

Please don't try anything else.