Many companies still make AM/FM dedicated tuners. Yamaha for one, see the link below. $250 new. You seem to already have plenty of amp and other devices, just need the tuner. I think that you can find tuners like this without needing to go some over-the-top complicated setup.
https://usa.yamaha.com/products/audio_visual/hifi_components/t-s500/index.html
https://usa.yamaha.com/products/audio_visual/hifi_components/t-s500/index.html