In the "inspection world" the electrician has altered a listed piece of equipment which could deem it unacceptable.
That said, I have seen similar procedures done often and accepted
Before I proceeded, I would talk with the inspector and see exactly what his concerns are.
There are a multitude of potential violations in the changeover.
If 'altering' is his concern, then you have little choice but replacing the panel.
At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at at time.