OK, let's try this again.
I bought this revolver brand, spanky new in 1975. It is a EuroArms 1858, actually made by Armi San Paolo.
Here is the Armi San Paolo stamp.
The first thing you should notice is how tall the front sight is. I'll bet you the front sight on your EuroArms Remmie is not that tall, if it is from that era. Compare them. Back when I bought this gun they were usually shipping with a much lower front sight. And they usually shot high. So the first thing I did before I invested in a conversion cylinder is I had a gunsmith install a taller front sight. A 45 Colt cartridge with a 200 or 250 grain bullet is going to recoil more than your typical round ball with around 30 grains of powder, and if anything a cartridge conversion will shoot even higher with a short front sight than it will with Cap & Ball.
That is actually an Uberti front sight on this gun. I bought the part from VTI, it was dirt cheap, and I had a local gunsmith cut a new dovetail for the front sight; it required a bigger dovetail than the original sight used. Then I shot it C&B to make sure it was printing lower with the taller front sight than it used to.
Here is a close up of the Uberti front sight installed in the old EuroArms revolver.
Once I was happy with where it was shooting I had the conversion cylinder installed. This particular cylinder is the six shot, 45 Colt cylinder marketed exclusively by Taylors.
http://www.taylorsfirearms.com/
As I said in a different post, Taylors has exclusive rights to this particular cylinder, anybody else who is selling it is buying it from Taylors.
Now here is why you should call up Taylors and talk to them. Seeing as I had a pistol that was neither Uberti nor Pietta, just like you I was not sure what cylinder to buy. By the way, even though they are advertised as dropping right in, there are instances where a minor amount of fitting has to be done anyway, usually relieving a little bit of the frame at the front lower corner where the cylinder sits. Despite everything you read, it is next to impossible to get a true drop in on every gun. Sometimes a little bit of fitting has to be done.
So I called up Taylors. At that time, they had a fantastic policy. You send them your gun, and they fitted a cylinder to it FOR FREE!! Yes, for free. Taylors employed a gunsmith on site who was doing this work. He had a special fixture that the gun was mounted in. Using the gun in the fixture he did some set up work. Then he removed the gun and he took a 'raw' cylinder, which did not have the locking slots cut into it yet. He mounted the cylinder on the fixture and cut the slots into the cylinder so it would perfectly fit the specific gun. No modification at all to the gun, just fitting the cylinder. The gunsmith's name was Tom, and I had a couple of conversations with him while he was doing the work. He told me he used a Pietta cylinder for my gun. It was the right diameter. He did have to face off a few thousandths off the front of the cylinder, so it would fit into the gun. Then he did the custom cutting, then he sent it out for rebluing next time he had enough to send out.
All of this FOR FREE!!! I paid the freight to send Taylors the gun, and of course I paid for the cylinder. That is all I paid. I did not even have to pay to have it shipped back to me, they shipped the gun on their nickle. They shipped it back with the original C&B cylinder installed, so it was not a firearm according to the ATF. The new cylinder was in a little box packed inside the shipping box.
I even had somebody dispute me, telling me that it was too expensive to do all that for free, but that is the truth, that is what they did.
You really should give Taylors a call and see if they are still doing this service. Even if you have to pay for it, you will probably get a better job then with most gunsmiths, because they are set up to do this work, and I'll bet they won't charge much.
By the way, I usually shoot it with 45 Schofield cartridges, not 45 Colt. A full house load of about 35 grains of FFg Black Powder with a 250 grain bullet recoils right smartly. Even though I can shoot them all day long in my Colts, the grip frame of the Remmie is slightly different and shooting those rounds is punishing. So I usually shoot it with 45 Schofield cartridges with about 28 grains of FFg and a 200 grain bullet. Much less punishing. When I first bought the cylinder, the counterbores for the rims were not quite large enough for the larger diameter Schofield rims, and they would jam. A friend opened up the counterbores for me enough that now it will accept both 45 Colt and 45 Schofield rims. But don't worry, they have fixed that and the the newer cylinders will accept both cartridges.