I find myself in complete agreement with the opinion-page column "How Best to Aid the Republics," Oct. 1. The Soviet republics must be aided if they are to have a chance at survival, but why should the US, one of the world's largest debtors, lead the way in providing aid?Why shouldn't the International Monetary Fund and the World Bank take the reins as financial overseers of the reconstructing republics? This would have the benefit of avoiding actions that might be interpreted as US intervention and of including other Western countries. This much is needed, since no one country can take on this program alone. Ryan Keaton, Florence, Ala. Letters are welcome. Only a selection can be published, subject to condensation, and none acknowledged. Please address them to "Readers Write," One Norway St., Boston, MA 02115.