I recently purchased a home that was built in the mid 1970's. The family that built the home decided to go with a round commercial style recessed can light where the bulb is completely enclosed behind a glass lens. The lens assembly is hinged to provide access to the underlying bulb. The hole in the drywalled ceiling is just shy under 12 inches in diameter!!! Tearing down the drywall is not an option because there are around 20 of these throughout the home. What are my options in replacing these fixtures with a 6 inch can or similar? What are my options at this point?