I have pulled many sets of injectors from cars in the yards. I have only found one set of injectors that were in good enough condition that I did not even want to open them up for cleaning. I sold the set to a forum member a while ago. For the cost of the injectors, shipping them to be reset, the labor, the cost of shims/springs, etc; it would be better better invested in a set of fresh nozzles and there are several people on this site who charge a reasonable rate for a rebuild. Myself and Greazer being two of the people.

You probably need new injector nozzles if you are certain they have never been rebuilt in the 300K miles. A pop test is the only way to be certain, though.

That is a really good deal.