twain = two, Anglo-Saxon twegen (= twain) is masculine, trd is feminine, and twa, or tu, is neut. So that "twain "is better, as the masculine takes precedence of feminine.
one = for, or unto. Greek. eis.App-104. Not "become one" (as Revised Version)
but = shall be, or stand for one flesh.
no more = no longer. Greek. ouketi. Compound of ou. App-105.