Place the shrimp stock in a medium saucepan over medium-high heat. Add the Roma tomatoes and bring to a simmer (do not allow it to boil).
Simmer the sauce for 90-120 minutes or until there is about 2 cups of liquid (including the tomatoes) remaining.
Remove from heat and let cool.
Pass the sauce through a wire mesh strainer, pressing all the liquid out of the tomatoes. Discard the tomatoes.
Place the sauce in a small saucepan over medium heat and simmer until it is reduced to 3/4 cup.
Add the salt, butter, wine, and tomato paste and stir until the butter is melted.
Remove from heat and set aside. (The sauce can be made up until this point and refrigerated until needed. The sauce will keep well, refrigerated, for about 48 hours. Warm the sauce in a small saucepan before adding to the pasta.)
When ready to serve:
Place the water in a large saucepan over high heat. When the water boils, add the pasta.
When the pasta is close to done, place the olive oil in a skillet over medium-high heat and add the white part of the green onions. Cook for about 1 minute and add the shrimp.
Cook the shrimp for about 5 minutes, turning frequently, until the shrimp are almost cooked through.
Add 6 of the grape tomatoes and cook for 2 minutes, tossing frequently.
Drain the pasta, then add the pasta to the skillet along with the shrimp sauce and the green part of the green onions. Toss for 1-2 minutes and serve topped with the remaining tomatoes as garnish.

