I shoot one regularly with a .45 LC conversion cylinder, 45 ACP observations would likely be almost identical.
My personal belief, held for a number of reasons, is that the nicest Walker replica today is the Uberti as imported by Taylors. It is top quality, devoid of garish markings, well finished, and well supported. The other choice would be a Pietta, which will likely be a bit less expensive (not by much), is also well built and finished, but in my personal experience not as smooth out of the box, and is afflicted with what are to me absolutely terribly placed markings on the side of the BBL "Made in Italy" and "Black Powder Only" as opposed to the discrete markings under the loading lever of the Uberti product. Different people have different opinions... mine is that this detracts sufficiently from the Pietta as to exclude it from my consideration. Some folks love Piettas. I do not. That's what makes a horse race though. Look at both before you buy either.
The conversion cylinders are top quality items, are specific to either Pietta or Uberti (make sure you get the right one), and interchange with the original cylinder with ease. The Walker is a large and heavy revolver, really oversized for either the .45 LC or .45 ACP. It suffers the original Walker revolvers flaw in that the loading lever will often drop under recoil, locking the cylinder for the next shot until manually raised back to position. You can cure this with a leather thong to hold it in place, or do what I would suggest, and that is to reconsider the Walker, and procure it's follow-on, a Colt Dragoon replica, of either first, second, or third model variety. These have all of the ""Charm" of a Walker, but have a far better loading lever retention system.
Really... there are other cap and ball replicas that are likely nicer cartridge conversion platforms (1858 Remington is my own favorite, followed by the 1860 Army), but since you have specified a "Dragoon" in the form of the "Walker Dragoon" I'll not go into detail on the others unless you express an interest in them as well.
I am presently shooting cartridge conversions of 1847 Walker, 1851 Navy, 1858 Remington, 1860 Army, and 1861 Navy (all Uberti), so ask what you like. They are a lot of fun, and are a great way to enjoy these.
BTW: Both the .45 LC in the loads suggested for the conversion cylinders and the .45 ACP are anemic compared to the original 60 grain black powder loading in a Walker, so it's hardly an "Upgrade"