Guardian structures provides a means to retrieve Guardian Blueprints for various engine parts
New Growth station is the closest station at 102 Ly away from the nearest guardian structure. It is an asteroid base which, usefully, has a shipyard. You can use the neutron star in system Vela Pulsar for an FSD boost in order to shorten the trip either way.
As you approach your Guardian Structure planet consider pausing and mapping the planet with a detailed surface scanner if you have one. Synuefe NL-N C23-4 B3 planet A4 and Synuefe NL-N C23-4 B3 planet A5 are terraformable planets, making them particularily valuable.
Col 173 Sector GS-J B25-4, planet D2 (around 30.000 ls from the main star) is recommended for the module blueprints. It is much easier, because it is usually much brighter there, the gravity is friendly, and the nearby terrain is very flat so that landing a large ship close to the structure is easier. This system also has some Notable Phenomena and a terraformable water world near the entry star.