Cook unpeeled potatoes in boiling salted water until tender (about 35 minutes). While potatoes are cooking, split garlic and place it in a jar with oil; let stand for 10 minutes. Remove and discard garlic. To oil, add vinegar, salt, sugar and dillweed; shake well to blend. Drain potatoes; peel while warm and cut into 1/4-inch cubes (you should have about 4 cups). Pour dressing over warm potatoes. Cover and chill for several hours or overnight. To serve, slice 2 eggs. Add to potatoes-with green onions, radishes, green pepper, ripe olives and mayonnaise. Mix lightly. Slice remaining eggs and use, with parsely, as a garnish. Serves 4.