The current LDS text retains the original singular was in this verse, but the RLDS text has had the plural were since the 1953 edition. This grammatical emendation relies on interpreting peace and the love of God as different entities. One could argue that the singular was is acceptable since the love of God and peace co-occur and are manifestations of the same thing. In fact, this close relationship may be the reason why the LDS text has never been changed to the plural were in this verse. In a noun phrase like “law and order”, the associated verb can be in either the singular or plural: “law and order is crucial” or “law and order are crucial”, the choice depending on whether one interprets law and order as manifestations of the same thing or not.
Another example of where this issue arises in the Book of Mormon text involves the two nouns faith and hope:
By replacing the original singular is with the plural are, the RLDS text (except for the 1908 edition) has treated faith and hope as distinct entities, yet semantically they can be considered manifestations of the same thing.
In any event, this semantic issue is irrelevant as far as establishing the original text for Jacob 7:23 (and Moroni 7:44) is concerned. The earliest textual sources read in the singular, and therefore the critical text will accept the singular verb form. There is nothing textually inappropriate about the original reading in Jacob 7:23 since the original text had many examples of was taking a subject noun phrase composed of conjoined singular nouns, as in Alma 15:3 (“for he supposed that Alma and Amulek was no more”) and in Alma 58:17 (“now Gid and his men was on the right”). For further discussion, see 1 Nephi 4:4 as well as subject-verb agreement in volume 3. The critical text will maintain the singular form was here in Jacob 7:23, no matter how the conjunctive subject is interpreted.
Summary: Maintain in Jacob 7:23 the singular was since the earliest textual sources read this way; in this instance, the question of whether the conjoined noun phrases peace and the love of God are semantically similar is irrelevant in determining the reading of the original text.