If you replace the nickel crown there is the possibility you will be getting palladium mixed in with the gold,(even if they say you wont.) Crowns are often sent out to places like Thailand for the CHEAP LABOR. Can you really trust them to use pure gold platinum?
Best replacement,Gold/PLatinum liner fused to porcelain,or all porcelain.
Disturbing the tooth can cause problems and lead to a root canal which is even worse.