GMAT Sentence Correction (SC) | Re: In 1860, the Philological Society launched its effort to

Though I can reach the supposedly correct answer through the process of elimination but would is also used in the context of making a prediction about the future but in the past. However, is it correct to express the result of a prediction right after it? I am still not comfortable with this construction 'would take more than 60 years to complete, the Oxford English Dictionary was' Can @e-GMAT comment on this