Ness_c7
Good luck. I hope that you can get the radio to sound good over the background of the Mini.
I tried to fit a very modern FM radio IC (from the Jaycar "Cardboard Radio") to a gutted Ferris Portable radio along with a 20 Watt stereo amp. They use the original radio switches, tuning and volume controls. The FM radio is not worth the effort, but I also fitted a line input from a phone. Using "i-heart", the phone can receive AM or FM radio stations with better quality than the Ferris brothers every dreamed of.
I could not bring myself to trash a working vintage radio, so I did a line input for an AWA Pressmatic that I have had since the 70's. The wiring is the same as on a youtube for vintage valve radios at
https://www.youtube.com/watch?app=desktop&v=j8YeJ0T3DpI Another option is a "Bluetooth Receiver Amplifier" from Core Electronics in Newcastle. (XY-P40W) Only about $20, great sound quality, tiny and you might be able to fit it outside the Leyland radio but using the radio power switch so it looks like the radio is working. The metal case of the radio would block the Bluetooth signal so it would not work inside the radio case.
Good Luck Dave D.