Priv Key with 58 characters to WIF I have an old paper wallet with Private Keys of 58 characters (all starting with a 6). These can be imported e.g. on blockchain.com, but since I still have BSV on this key, I have to import/sweep it in ElectronCash or ElectrumSV, which doesn't take this format. 
So, does anyone know, how to convert this key into WIF (without coding if possible)? Thanks in advance!
A private key starting with a 6... and being 58 characters long.. sounds to me like you encrypted another private key with BIP38?

Simply decode the private key using a third party tool and then import the decrypted private key into ElectrumSV.

consider the following  private key; L4GPduQvHAhFrpnF5x29N7UV8x5iLqxKRWArfHvJn4PwtZu35Uur and subsequent adress - 1He7vZABE7Um1dZG8b1sRCZLnXD3DX4ebB 

which encrypted with password ppg gives the following 58 char bip 38 private key:
6PYKwd9VQNQsmEzy4UqKBDLQ6DhMUxzLGjgzmqzZSAuqm82EPg9HhRM6Qd 

To decrypt this without coding, i suggest you use something like Ian coleman's templates, or those of bitaddress.
https://www.bitaddress.org/ download the repository, https://github.com/pointbiz/bitaddress.org , verify it, then run the HTML file. 

Go to wallet details = > enter your encrypted private key ( in my case ; 6PYKwd9VQNQsmEzy4UqKBDLQ6DhMUxzLGjgzmqzZSAuqm82EPg9HhRM6Qd and tick the "BIP38" encrypt box and fill in the password; which for me is " ppg "
then; you get a couple private keys; compressed || uncompressed in your case.

in my case; i simply see the compressed private key i encrypted, and the uncompressed key; which i wouldn't need in this case, as my balance was on 1He7vZABE7Um1dZG8b1sRCZLnXD3DX4ebB (belonging to the compressed key.)

See which one match the adress holding the balance, and import that private key into electrumSV. You'll have to figure which derivation paths to use yourself i'm afraid.