To answer your question, your fine as is. You will need a hose from your new cylinder to the "T" attached to your tank. You can go to a lot of places to buy the hose you need to attach your new cylinder to the fitting you have now. Pretty much it is a hose with a Type 1 tank fitting and a fitting that is the same as the fitting on a 1lb bottle. If you already have a hose with a POL fitting you can use that one.
Simple no big deal.
By the way, Marshal Brass is now Marshall Excelsior Company and Extend a Stay is Sturgisafe. Camco also carries all the fittings but all you need is the hose.
