I also did this method. I did try one private key with a few bch to see that is working or not. Then no problem, I sent all bch using Electron cash to coinbase.
If you are sure that the keys are not in use for the main chain, then the easiest is to use Electron cash (or similar). That means that you won't have to download the entire bitcoin cash chain (as you would with the abc client).
I think Bitcoin.com wallet also protects your keys somehow.
Presumably, you just want to send your coins to an exchange?