Although I'd like to see a peace-time Republic myself, I think holding out for one would be a foolish move at this point. All the other AI civs are Monarchy. These, of course means that they now all have a more productive government than us. Our only lead at this point is the Construction over Babylon. We need to become a Monarchy now so that we do not fall behind. If we crank our Sci rate up to 80% (-4gpt) we can have Currency in 8 turns. This will jetison us into the Middle Ages. Once there, we should research Monotheism, Theology, and Education. Period. This will eliminate the Great Library. If we waste time trying to get the Republic tech, we will lose our edge. This is a very crucial decision, and trying to become a Republic will keep us at a mediocre and forgetable civ in 4th place. Once we get Education and then Gunpowder, we can go for and become a Democracy. I repeat, trying to become a Republic would be a mis-step.