I don't think I'd sandblast it. I think you'd run the risk of wearing down the detail, even with walnut shells. I'd opt to strip it in place, or take it down and strip it outside and re-install afterward. I'd use one of those peel-able strippers to try and get the paint and gunk out of the bead. A tedious, but do-able proposition, at least I hope so as I have a whole room and ceiling that's on my list for that treatment this Spring. Fortunately mine isn't painted, but the varnish has become blackened and needs to be removed. If you ask me again after Labor Day, I'd have some experience to offer, rather just a plan. Molly~

Solid wood paneling is a classic, very valuable and cannot be replaced. I'd do something to keep that. I agree that the original aesthetic of the wood was to add warmth with all the natural hard materials like stone, slate, iron, etc. Depends on how much of a purist you want to be with the aesthetic. The original design is flexible as to what colors and stains would work. You could paint too. The only real crime would be to tear out something that is as valuable as real wood paneling. It was even expensive back in the day when it was installed. It has value because it is high quality and beautiful. I would seek to do something that retains the pluses. If you want to maintain your house as an homage to the middle of the last century, then obviously "restore" rather than "redo." Oh, and just a ponder, is that two story fireplace material original? Or was it originally brick too? Love your house BTW! Very elegant.

It's too late to paint (at least for the stuff already installed). Wood must be painted on all 6 sides, otherwise it will cup badly with changes in humidity (the unpainted side will absorb moisture much more easily that the painted side). This will be worse with the wide boards you are using.

I wish I had painted the sides of my bead board ceiling boards. However, I'm wondering, do you mean actually paint the entire board before installation? What about nail holes afterwards? they would need to be filled, sanded down and then repainted, but I guess it wouldn't be such a big deal. In fact I'm betting the entire ceiling would have to be painted again due to smudges and such from the work of the installers. ETA: that is a good point about sanding before priming. I did that, and now I see I could have saved myself a lot of work if I hadn't.