Brian doesn't need Jeff Lynne to produce a record. Lynne is a master producer, of course, and I dearly love and have been influenced by the music he made, but his production mindset isn't the same as Brian's. That's about all I can say unless anyone wants to discuss more details on that.
The trap that seems to exist in any legacy artist especially those from the 60's is that many have a fantasy of them cutting records "like they did in the old days", like a vintage time warp back to 1966. many have tried, and tried very hard to get every detail right down to using vintage guitar cables and patch cords for fucks sake, but does it ever work? Is there ever anything close to the records being copied?
My dream Brian Wilson project is to let Brian do what he wants to do, cut some tracks, and I'll listen.
Most definitely agree that a truly Brian-centric project (meaning something as close as possible to Brian writing everything himself and recording it solo or nearly solo) is my desire as well.
But *if* we had to have a project where a collaborator/co-producer has a heavier hand in the process, Lynne would be my first pick. Yes, it would sound relatively different from Brian solo albums of recent years, especially sonically. It might in some cases, like "Let it Shine", sound like Brian singing a Jeff Lynne record. But I think it could work quite well; Lynne is sympathetic in a way that some other producers might not be. They speak fondly of each other despite a pretty short-term collaboration 30 years ago. Plus a big benefit for Lynne is that he's a singer and musician and songwriter but can give you any artist/producer split that is needed. If you just need a guy "producing" and nothing more, Lynne can do that. If you want some musicianship but not songwriting input, he can do that. If you want more involvement and some backing vocals and stuff, he can do that. If you want to co-write, he can do that. If you want finished songs, he can hand you those too.
But again to reiterate, I'd love a truly all-Brian album with 12 to 15 "Message Man" type tracks.