Preheat the oven to 350 degrees F (175 degrees C). Rinse the calamari tubes and pat dry.
In a large bowl, stir together the onions, 6 cloves of the garlic, shrimp, crabmeat and lemon juice. Spoon some of this mixture into each squid tube and seal the ends by 'sewing' with a toothpick. Arrange in a single layer in the bottom of a 9x13 inch baking dish. Set aside.
Melt the butter in a saucepan over medium heat. Stir in cream cheese and 2 cloves of garlic. Cook and stir until cream cheese has melted. Gradually whisk in the milk. Cook until heated through and then remove from the heat and stir in the Parmesan cheese and pepper. Pour over all of the calamari tubes in the baking dish. Sprinkle about 2 tablespoons of Romano cheese on top of each one.
Bake uncovered until the cheese is browned and sauce is bubbly. While the calamari is baking, Bring a large pot of lightly salted water to a boil. Add linguine pasta, and cook until al dente, about 8 minutes. Drain. Serve the stuffed calamari and sauce over a bed of linguine.