To get 350+ at 1 bar the turbo would stand out as not being a T3, or a T34, I would just ask for proof, you can't tell a thing by looking at a ecu, other than it is a certain sort ie L1/6/8 or the ecu chip has been changed, other mods will be needed, the biggest immediate clue is the colour of the injectors, as these would need changing as would actuator, and at 350+ the intercooler needs to be a 4wd one not 2wd and would normally be a RS500 type, it would need the usual exhaust air filter swap etc as well.
tabetha