Cook salt pork in a large Dutch oven over medium heat until crisp. Remove salt pork and discard; add onion to drippings in Dutch oven, and sauté until tender.
Add potatoes, tomatoes, red pepper, and water. Place allspice and cloves in a small cheesecloth bag. Tie securely, and place spice bag in Dutch oven. Bring to a boil. Reduce heat; cover and simmer 1 1/2 hours.
Soak biscuits in milk until all liquid is absorbed; add toast and clams to Dutch oven, stirring well to break up toast. Simmer an additional 15 minutes.
Remove spice bag and discard; season chowder with salt and pepper.
Ladle chowder into individual serving bowls; serve warm.