Wash the chicken under cool running water and pat it dry with paper towels. Refrigerate, uncovered, for at least 12 hours and as long as 2 days.
Preheat the oven to 425 degrees F. Oil a roasting or baking pan with canola oil.
Make the stuffing: Put the breadcrumbs in a medium bowl. Heat a large skillet over medium-high heat. Sprinkle the liver and gizzard with salt and pepper. Add 1 tablespoon of the butter to the skillet and when it melts, add the giblets and cook quickly until browned on both sides, about 3 minutes. Transfer them to a cutting board, chop finely and add to the breadcrumbs. Off of the heat, add the wine and scrape the bottom of the skillet to dislodge the brown bits; pour the liquid onto the breadcrumbs and mix.
Add the pork to the skillet and cook until browned, about 5 minutes; scrape the pork into the bowl with the bread mixture. Add 3 tablespoons of the butter, the onions and 1/4 teaspoon each salt and pepper to the skillet and cook over medium heat until the onions are soft and tender, 10 to 15 minutes. Add the sage and garlic and cook 1 minute longer. Add the Swiss chard and cook until wilted. Scrape the mixture and all the buttery juices onto the breadcrumbs and mix to combine. Add the chives and lemon zest and taste for seasoning, adding more salt and pepper if needed.
Loosen the skin over the chicken breasts. Insert the remaining 4 tablespoons cold butter under the skin of the chicken breasts, pushing down to disperse them. Rub the chicken all over with a thin film of canola oil. Sprinkle the chicken heavily on all sides with 3/4 teaspoon each salt and pepper. Stuff the cavity with the bread mixture, and stuff the neck skin with any remaining stuffing. Set the bird in the oiled roasting pan.
Roast the chicken until the skin dries and the butter melts, about 15 minutes. Turn the heat down to 375 degrees F and continue to roast, basting the chicken once or twice with the fat that accumulates in the corners of the pan, until the thickest part of the thigh registers 170 degrees F on an instant-read thermometer, 45 to 55 minutes.
Transfer the chicken to a large platter to rest for 5 to 10 minutes. Strain the pan juices into a bowl and skim off the fat. Pour 1/4 cup water into the roasting pan, set it on a burner on high heat and scrape up any stuck-on bits on the bottom with a rubber spatula. Return the defatted juices to the pan and simmer together for 3 to 5 minutes to make a thin, natural gravy. Season with salt and pepper.
Carve the chicken on the platter. Slice the wings at the joint, twist to remove them and set them above the chicken. Cut the thighs at the joint, twist to remove them, slice them diagonally at the leg joint to separate them into thigh and drumstick and lay them on the platter. Carve thin slices from the breast meat and let them lay as they fall; pour a little gravy over the white meat, avoiding wetting the crispy skin of the thighs. Cut the stuffed neck in slices, and serve with the rest of the gravy in a small pitcher on the side.