If it could be done as a "repair" then the panel could be left in the closet and maybe even replace guts with one of those "new" retrofit kits.
What is the age of the "service"? I suspect that in this case the insurance company will not be satisfied unless the outside service is replaced also. Citizens Insurance when it wants a panel changed simply because of age wants the entire service replaced not just the inside panel.
Reminds me of the FHA homes where they required the SEU service riser was required to be in RMC conduit.
They did not care if the service size was ample or if wiring practice was correct.
Just put the service in rmc and verify all outlets worked.
I am talking the 70's but it was still crazy then.
All that was required was to install the RMC riser and verify all outlets in the home worked.