Sorry for not getting the "meat" answer.
YES; wire the existing circuits to a new loadcenter. And, anything that you have done/do "new" goes in with ground conductor in the RX.
The FPE panels (actually the breakers) have a reputation for not tripping, thus the "fire hazard". There are proponents of FPE, who insist that it's a "good product"; and there are many detractors. Funny thou, if it's a good product, why are they "out of business" as FPE?
John
