Is it possible to start a new chain with a specific difficulty?

Question

We already have a chain running using permissionless PoW. We called that the "testnet". Soon we would like to migrate to a "mainnet". Essentially, it will be just cloning the existing "testnet". All of the miners will move over to that new chain. Since we have established a good difficulty value, we would like to start the new chain with that same value. getmininginfo returns:
{
    "blocks" : 3788,
    "currentblocksize" : 1000,
    "currentblocktx" : 0,
    "difficulty" : 1.52587890625e-5,
    "errors" : "",
    "genproclimit" : 1,
    "networkhashps" : 14351024,
    "pooledtx" : 0,
    "testnet" : false,
    "chain" : "main",
    "generate" : true,
    "hashespersec" : 1015190
}

Answer 1

Yes, you can approximate any given difficulty level using the pow-minimum-bits blockchain parameter, when used to start a chain. The conversion is a little complex, so we recommend using trial and error of this pow-minimum-bits parameter to get close to the desired difficulty value in the output of getmininginfo.