mauro, to the best of my knowledge, old injectors usually leak and are not able to build pressure to produce spray. That causes rich condition. If someone leaned the car to compensate for leaking injectors, with new injectors you will have lean condition, the car will not work.
Most likely you will get a new set of injectors form the same production lot as those you had - if it was wrong, it will be wrong. To determine if the injector is ok or not, you need a tester or you need to fit it on the line without fitting it to the intake manifold, crank the engine and see if it is spraying fuel. It will not tell you, however, the opening pressure.