Shop owner to shop owner, when I do work like that I tell the customer Up front It will be charged as time and materials. When you start cleaning 45 years worth of grease/paint and road grime and then painting parts and all the other things that go along with it the time adds up. Im not here fixing this crap because I have nothing better to do and im good at what I do. I can put a set of pads and rotors on a Honda accord and make good money much faster and not clean anything. that takes an hour. A few of those a day is all I need. That said charge him what you feel is fair but show him your total hours for the job. If they don't like it they can spend 35 years learning how to do it. People pay to have their cars fixed because they cant do it. You have the knowledge, shop space and tools. all cost money. Just make sure its done right......Bill it out