I'd go for MP3 V0 instead of 320kbps. Most will agree that the quality is the same but the size difference is quite noticable. I mean as long as you're going lossy, you might as well be efficient with it and not throw away space.
I tried Lidarr but gave up on it and I'm just using Beets right now for organizing and converting my stuff. I don't download music so often and a bit manual work isn't an issue for me. I use FDK AAC and encode everything to VBR4 which is then available in Navidrome, but keep the FLACs of course.
There's barely a chance an excellent set of ears would hear the difference...but nevertheless, a set of excellent ears would go for FLAC anyway.
I can't hear anything above 15KHz and in all of the ABX tests I ever did I couldn't really hear a difference, at least with the best equipment and headphones I've had, so even V0 is an overkill for me but still much more efficient than FLACs
Being an audiophile is a rich people's game, the one I'd like to taste but wouldn't like to get into. The sole reason I keep FLACs is for archival purpose of music because lossy formats barely have any archival value, and you can always transcode FLACs into some better lossy format that might release in the future.