To make puree, cut guavas in half, scoop out pulp, and run through a colander. Save shells for other recipes. Chill evaporated milk by placing in freezer section for a short time. Pour into chilled bowl and whip until thickened. Add sugar or honey and lemon juice to puree and mix until sugar dissolves. Fold whipped milk into guava mixture and pour into freezer trays. Freeze 4-6 hours.