When designing DC-traction substation equipment some special requirements have to be considered:
Usually such rectifiers work with natural cooling which is quite unusual for rectifiers of that rating, efficient design requires heatsinks with a special design
The rectifier and the transformers has to be designed to be able to work according to the load profile, e.g. to be able to provide higher current than rated for several hour during rush hour
Rectifier and transformer have to withstand a short circuit until the breaker trips. Fuses are only used for removing defective diodes from the circuit
Beside this the transformer has to be designed for rectifier operation (to cope with nonsinusoidal currents) which is not an easy task in the power range used for that application.
If you are not willing to spend at least half a year of development and design time on that topic leave the order to companies already having 50 years of experience in that business.