Wash and drain rice. Heat 3 Tbsp of the olive oil in a skillet over medium-high heat. Add the yellow onion and saute until soft but not brown, about 5 minutes. Transfer to a mixing bowl and add the drained rice, 1/2 cup of the remaining olive oil, green onions, parsley, pine nuts, cinnamon, allspice, salt, and pepper. Set aside.
Rinse the grape leaves under running cold water to removes as much brine as possible, pat dry, and stack on a plate. Place 1 leaf at a time, shiny side down, on a flat work surface. Cut off and discard the tough stem end. Spoon about 1 Tbsp of the rice mixture in the center near the base of the leaf. Fold the stem end over to cover the filling, fold both side inward lengthwise and then tightly roll leaf toward pointed tip end to form a compact packet. Repeat with the remaining leaves and filling.
Pour about 2 Tbsp. of the remaining olive oil in the bottom of a large pot and strew with a layer of parsley stems to prevent grape leaves from sticking. Arrange the stuffed leaves, seam side down and almost touching, on top of the parsley, making as many layers as necessary.
Drizzle the remaining 5 Tbsp olive oil, the lemon juice, and 1/2 cup stock, broth, or water over the leaves. Top with a heat-resistant plate and weight with a heavy can to keep leaves from unwinding during cooking. Cover the pot, bring to a gentle boil, reduce the heat to low, and cook until rice is tender, about 1 hour.
During cooking, add a little heated liquid as needed to keep dolmas moist. Remove from the heat and cool in the pot. Sprinkle with lemon juice to taste, garnish with lemon zest, and serve at room temperature.