Zevahim 76: Allowing Terumah - Maybe

Money from the sale of shevi'it produce cannot be used to purchase terumah produce, lest the permissible time to eat the produce be too limited. But Rabbi Shimon seems to allow terumah spices even when one might have thought the permitted time period is long over. With several cases of back and forth on his views. Also, when the stringencies of both guilt-offerings and peace-offerings - for example - were necessary.