I think I have a dust covered Alpine shaft radio in my tool room. If I had to guess the belt in the tape drive has past it's prime and the cassette might now work.
You can cut that opening to fit a DIN radio and it looks pretty good. I used to do it all the time when I was an installer in the 90's.
Since you only want a radio you should be fine. You can't have a CD player with a shaft style as the opening is too small for a disk to fit. The only way to have CD and shaft is to find a changer controller and external changer (or half ass it with an FM modulator).