On your ignition switch, there is one terminal that is connected to the ammeter. This is the feed to the switch and it is always live. There are one or two other terminals that are wired to things like the ignition coil, the heater and the dash lights and gas gauge. I am suggesting that you add your radio feed with the inline fuse to one of the two switched terminals. This will make sure the radio is off when the ignition is turned off.
By the way, don't worry about asking questions. We all do a lot of that and it is what the Stovebolt is all about.