For the corned beef and cabbage: Pour the stock into a large 4-gallon stockpot over medium-high heat and bring to a simmer. Add the pickling spice, garlic, bay leaves and cloves. Reduce the heat to medium, then add the beef and cabbage simmer until tender, 3 hours. Season with salt and pepper.
Slice the corned beef into thin slices against the grain. (This should yield around 30 slices.) Slice 2 wedges of the cabbage thinly.
Butter 1 side of the bread slices and brown on a warm griddle or large nonstick pan. Top each bread slice with 1 slice of cheese, followed by Thousand Island dressing. Add beef slices to half the bread, and the cabbage to the remaining bread slices. Continuing browning the bread for 2 to 3 minutes, and then assemble the sandwiches. Warm the assembled sandwiches in the pan or a preheated 350 degrees F oven.