ὡς is clearly right. The ὥστ̓ of the MSS. would mean, "and so" (i.e. since they are the Eumenides). It could not mean, "and in that case," i.e. "if they prove kind." ὡς is best taken as simply causal, "for" ( schol. “ἐγὼ γὰρ οὐκ ἀναστήσομαι”), rather than as="know that" ( Eur. Phoen. 1664 “ΚΡΕΩΝ. ὡς οὔτις ἀμφὶ τῷδ᾽ ὑγρὰν θήσει κόνιν”). γῆς: cp.
. Eur. Helen 797 “ὁρᾷς τάφου τοῦδ᾽ ἀθλίους ἕδρας ἐμάς;” >ἂν ἐξέλθοιμ̓: the optat. with ἄν calmly expresses a fixed resolve: cp. O. T. 343 “οὐκ ἂν πέρα φράσαιμι”.