Hello,
So if I understand correctly, you have SSG20 running 6.2.0r5.0 in the network.
And you have also purchased SRX320 and you intend to migrate the SSG20 configuration to SRX320.
Is that correct?
If yes, you can try the tool below:-
https://migrationtools.juniper.net/s2j/index.jsp
Regards,
Rushi