Toast the ancho and guajillo chiles in a dry skillet for 30 seconds per side until fragrant, then soak them in the 2 cups hot broth for 15 minutes.
Blend the chiles and soaking broth until smooth.
Place the pork, salt, onion, garlic, oregano, chile puree and remaining 6 cups broth in a 6-quart crockpot.
Cover and cook on low for 7 hours, stir in the hominy, and cook for 1 hour more until the pork is fork-tender and at least 145°F.
Stir in the lime juice and break only the largest pork pieces before serving.