Context: Pausanias, having learned that an junior associate is about to turn informer, pleads with him.
quo magis Pausanias perturbatus orare coepit, ne enuntiaret neu se meritum de illo optime proderet: quodsi eam veniam sibi dedisset tantisque implicatum rebus sublevasset, magno ei praemio futurum.
Translation: All the more disturbed, Pausanias began to plead that he [Argilius] should not inform, and he should not forsake one to whom he [Argilius] owed so much; and if he would grant this favor, and take away the difficulties entangling him [ Pausanias], there would be a big reward for him [Argilius].
orare coepit: I take orare coepit together as perfect tense. The time of the entreaty is in the past, and hence, enuntiaret and proderet are in the imperfect subjunctive. The action is for the future, that Argilius will not inform.
The clause beginning quodsi: is this a conditional sentence wrapped inside indirect discourse? Assuming futurum to be a future infinitive, that fulfills the rule for indirect discourse the infinitive is in the tense relative the time of the saying.
But I need help on the two pluperfect subjunctive verbs dedisset and sublevasset. I can’t cite a grammar rule for this tense choice. I’m having a lot of trouble finding a clear rule for this point.