Mr. I. If your 1976 CHB is anything like the 1974 MT we had, you can remove the "ceiling" liners/covers quite easily after removing the teak strips. The MT had a patterned vinyl type covering which I sprayed with a plastic compatible spray paint. Krylon brand as I recall. https://www.krylon.com/products/fusion-for-plastic/
As a testimony for the paint, I was looking for a 1 or 2 gallon yellow plastic fuel can for diesel for topping up my fuel filters. Couldn't readily find one so shot a red plastic gasoline can with yellow Krylon and after 3 years it hasn't deteriorated at all even in contact with the diesel dribbles.