Joining two gearboxes with in-wheel motor and replacing old hydraulic motor with electric one

The vehicle is large mobile working machine. I am combining two gearboxes with in-wheel motor and at the same time replacing old hydraulic motor with electric one. The electric motor would not fit to the same space with the previous hydraulic motor which has 300 Nm continuous torque and 390 Nm max torque. I want to keep the old gear with 1:17 ratio. At first I need to find out what is the torque of the same sized or smaller electric motor (because new gear needs to fit there too). Lets assume that the continuous stall torque of the electric motor would be 11 Nm and peak torque 44 Nm. What gear ratio I would need for the new one to combine it to the old 1:18 gear? How do I should calculate it? What other things I need to consider? How does the combining work in practice?