Cleaning any firearm is perfectly fine, but removing patina from actual historical arms isn’t.
While I agree with the first part of this statement, and am in partial agreement with the second, I would modify that part about "patina". Patina is nothing more than oil covered rust. Rust that used to be blueing. I would NEVER take the gun to a wire wheel and REMOVE the patina. What I DO do, is CONVERT it back in to blueing, which is what it was originally. Big difference. It's still working its' deviltry (albeit slowly) under that coat of oil. That's what gives it that chocolate color.
I have several older guns with varying amounts of "patina" on them, and, as my 2024 New Year's Resolution project, I'm reconverting that "patina" back in to blueing on those guns (on those that were originally blued) as appropriate. I'm not messing with the ones that were nickeled. It works best on guns that were originally rust or hot blued. Niter blueing is a slightly different color (more cobalt color) as is fire blueing (usually on small parts). I haven't figured out how to attack that yet other than re-fire blueing the screws. If the slots are buggered up I pound the metal back in to place with a small hammer and re-cut the slots if I have to.
To do that, you have to take the gun completely apart. (If there are staked parts you don't necessarily have to take them completely apart*.) Then boil all the parts for a period of time in regular water. That gets rid of all the old oil and sludge, (like decades old WD`40) and converts the brown inactive rust back in to active orange rust. Take them out, dry them, and card them. You can do it right away, as the rust that forms is fine grained "flash rust". You can use a very fine carding wheel spun at a slow speed, or 4-0 steel wool, or a carding brush. In places where the rust has raised little blisters, use a small (polished face) hammer and pound the blisters. That will flatten the surface and get rid of the blisters. You may or may not have to boil the parts again and repeat depending on the extent of the rust.
* with the staked parts you can boil the unit in a partially assembled state. The same goes for barrels assembled in to receivers. Just make sure to card as much as you can of it, and work all the parts several times while the unit is submerged in the kerosene (it's safer snd lead stinkyto use than diesel fuel or gasoline--WAY too dangerous!) to force the water out of there.
(This is a good time to kill any mold that may have started in the wood too, and do some clean-up with the finish.). I use vinegar and neutralize it with household ammonia. I don't want any of the acid residue touching the metal when the gun goes back together.
Then slobber on some old used heavy motor oil for a day or so (on the metal parts). That darkens it. Clean that off, and submerge the parts in a kerosene bath for another day or so. Work the parts you need to when everything is submerged** to force the water out. Now you can reassemble the gun with a light gun oil and it'll be good for a long time.
** If parts are riveted or staked to the wood use your own discretion in removing those. In any case don't boil the wood. That's not the best way to get oil out of there anyway, and is a topic for another discussion.
If you're going to take on this sort of a project for yourself, I would suggest starting with those specimens in the collection that are the least valuable and working toward those that are more so as you gain experience. Do the research. This is a "conservation and re-conversion" of what is already existing on the gun. Restoration is about replacing and adding things, like broken parts or adding more blueing. I suggest you proceed with judicious caution there. Replacing a broken spring or missing screw is one thing. Those were consumable parts that needed to be replaced periodically. Rebarreling is another. Those parts weren't.