Hello, I also have a vintage auto repair - resto shop. If it took 30 hours to professionally complete the job then that is what he should be charged. Not to sound rude but if he agreed to time spent and that is what it took then that is what it is. If you even gave him a range of cost before and it was low then you may have an issue. We are VERY upfront with customers that everything is TIME SPENT at our shop rate and I supply the parts as I refuse to have a lift tied up waiting on a customer to get the parts to me. I have been in the repair business my whole life ( 35 years) and used to get stressed about this kind of thing but finally came to the realization that I have to make as much doing this kind of work as I would doing general repairs. I WILL NOT loose money because someone thinks it should be cheap. If they have an issue with time and materials then they are not the customer you need. As far as 30 hours for everything you described that sounds about right. The cleaning, blasting and painting eats up a LOT of time.