Genesis.json add kovan or ropsten network

Question

Maybe stupid question but I am relative new to ETH.

This is my genesis.json for a private ETH node

{
  "config": {
    "chainId": 326432352,
    "homesteadBlock": 1,
    "eip150Block": 2,
    "eip150Hash": "0x0000000000000000000000000000000000000000000000000000000000000000",
    "eip155Block": 3,
    "eip158Block": 3,
    "byzantiumBlock": 4,
    "clique": {
      "period": 5,
      "epoch": 30000
    }
  },
  "nonce": "0x0",
  "timestamp": "0x5a8efd25",
  "extraData": "0x00000000000000000000000000000000000000000000000000000000000000003590aca93338b0721966a8d0c96ebf2c4c87c5448cc5a1a0802db41db826c2fcb72423744338dcb00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "gasLimit": "0xf42400",
  "difficulty": "0x1",
  "mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "coinbase": "0x0000000000000000000000000000000000000000",
  "alloc": {
    "3590aca93338b0721966a8d0c96ebf2c4c87c544": {
      "balance": "0x200000000000000000000000000000000000000000000000000000000000000"
    },
    "8cc5a1a0802db41db826c2fcb72423744338dcb0": {
      "balance": "0x200000000000000000000000000000000000000000000000000000000000000"
    }
  },
  "number": "0x0",
  "gasUsed": "0x0",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000"
}

chainId

is some random number. But I would like to use KOVAN or ROPSTEN ETH node for testing. I also do not want to retrieve all ETH blocks from the beginning but I would like to start syncing from some specific block. Is possible?

I found this https://hackernoon.com/set-up-a-private-ethereum-blockchain-and-deploy-your-first-solidity-smart-contract-on-the-caa8334c343d

The following network id’s are reserved for specific Ethereum networks.

0: Olympic, Ethereum public pre-release testnet
1: Frontier, Homestead, Metropolis, the Ethereum public main network
1: Classic, the (un)forked public Ethereum Classic main network, chain ID 61
1: Expanse, an alternative Ethereum implementation, chain ID 2
2: Morden, the public Ethereum testnet, now Ethereum Classic testnet
3: Ropsten, the public cross-client Ethereum testnet
4: Rinkeby, the public Geth PoA testnet
8: Ubiq, the public Gubiq main network with flux difficulty chain ID 8
42: Kovan, the public Parity PoA testnet
77: Sokol, the public POA Network testnet
99: Core, the public POA Network main network
7762959: Musicoin, the music blockchain
61717561: Aquachain, ASIC resistant chain

but not sure if is correct? What about MAINNET?

Thank you for all your answers