In book X of his Republic, Plato is talking about the prizes and rewards made out to good men. Once again, I have the gist of the sentence, but I'm a little unsure of a minor detail.
καὶ ἀνθρώπων ἆθλά τε καὶ μισθοὶ καὶ δῶρα γίγνεται πρὸς ἐκείνοις τοῖς ἀγαθοῖς οἷς αὐτὴ παρείχετο ἡ δικαιοσύνη, τοιαῦτ᾽ ἂν εἴη.
And the prizes and rewards and gifts of men are made to those good men whom justice itself produces, such as those that could be (exist?).
I think the majority of my translation is correct, although please correct me if any parts are wrong. The point of confusion is the phrase τοιαῦτ᾽ ἂν εἴη at the end. I have parsed εἴη as the 3sg pres. act. potential optative of the verb "to be". What's more, I have parsed τοιαῦτ᾽ as the nominative pl neuter of τοιοῦτος, tipped off by the elision which could only occur with an alpha at the end (as it would conflict with the alpha of the following particle). It's not surprising to see a singular verb go with a plural subject, as the subject here is neuter.
First, am I right to assume that the antecedent of τοιαῦτ᾽ is the prizes, rewards and gifts that were talked about in the previous clause? As a neuter subject, I reason that it can't possibly refer to the men (τοῖς ἀγαθοῖς) or justice (ἡ δικαιοσύνη) which are masculine and feminine respectively.
Second, is my translation "such as those that could exist" a good one? It's a little tricky to come up with a good translation for the optative, in this case. I'm a little torn between "be" and "exist", for translating the conjugated verb "to be".
In other words, I think what Plato is saying is that whatever prizes, rewards, and gifts could be offered, will be offered; I feel like this is the point of the final clause, i.e. τοιαῦτ᾽ ἂν εἴη.