An interior or a custom interior forum would be very useful for organizing or finding interior related topics. While initial thoughts of interiors might be truck year specific, I have been able to stumble across interior related ideas in various model forums to help my knowledge base and are applicable to my current 1948 Suburban build.
One current example is the tutorial Jim is sharing on making door panels...
http://67-72chevytrucks.com/vboard/s...d.php?t=662380. This should be located in an interior forum. Additionally, questions on how to or where to buy materials, carpet, seats, seat belts, paint finish, etc would likely be shared here benefitting the membership at large. I would see this as an addition to the general truck forums for suspension, paint, and audio.
Just one additional thought as an aside. This is the most enjoyable forum I am or have been a member of. The culture is positive, there is a fairly large nucleus of committed, and knowledgable truck enthusiasts and the drama is non-existant. Plus the vendor support and participation is exceptional. Well done!