To answer your question, I truly can't imagine wanting to restore the original interior on your 70's unit, I can't even imagine being happy with it when it was brand new!
I'm a high-end custom cabinet maker and a skilled craftsman, (plumbing, electric, welding etc.)
I gutted my '73 Sovereign
31' to the plywood floor.
I'll be totally remodeling the interior, eliminating the vertical divider walls and much of the upper cabinetry to open up the floorplan. Installing a custom interior equal to the ones Craig Dorsey does. (They're outstanding.)
I'm replacing all of the appliances and services with the best available.
I figure I'll spend every penny of $10,000.00 on equipment and materials alone.
I figure if I were doing it for a customer I'd want at least $40,000.
But that number is subjective, you get what you pay for. I'm sure I could provide a beautiful result, with less bells and whistles, for half that.