Painless success!
Thank you so much to you all for your answers and your time, you really made it all feel safer to do this!
I hope your posts will help others in the future, I sure will come back and read over it next time if I’m unable to sell my other coins to collectors over the next couple of years.
That's much simpler than creating a new online imported wallet with the private key.
The whole reason why cold-storage setup is recommended by the majority is for the safety of your coins while sending the bitcoins in case your PC is compromised.
It's not simple but the "air-gap" offline machine where the private key will be exposed is impervious to most hacking attempts.
Considering the amount contained in a Casascius Coin, I'd still wont recommend sweeping the private key on an online machine.