Yesterday I received my breakout from ABelectronics.
I buy it with 2 mounting pack because I'm going to interconnect the raspberry and the justboom amp hat.
Raspberry Pi <===/40===> Breakout Pi Plus <===/40===>Justboom Hat
Next step is to make a sketch of where I'm going to connect the rotary switch, which GPIO I'm going to use..
I'm thinking also about going to to an electronics shop to see what they have as rotary encoder.. I'm not happy with the idea of modify the hole on the old radio. Also, I was thinkins about the switch on the rotary encoder which are peraps to hard to push. I don't want people to hold the radio for pushing the button..