I am a also a general contractor , and I agree with south40. Replace it all. Sorry. As far as estimated cost . . . I am in the great costly to do business state of California - so out here, it would cost $100,000.00 dollars.
Good Lord that’s expensive!
I’m glad I’m competent enough to replace my 200 amp service myself. I had an old Fed Pacific panel that I replaced with a Siemens panel.
I started at dawn and was snapping in the last circuit at dusk. There were lots of circuits in my house and I eliminated baseboard heat in the process.
I’m not an electrician but was complemented by an electrician on the quality job. I’m slightly OCD so all of my wires are perfectly aligned and secured and everything is labeled. :)