I have 3 Remington 1858 NMA's, none of which are Uberti's but rather of the Pietta persuasion. I love'm all, VERY accurate and easy to care for.
I load them with 30 grs. of Goex FFFG,.... a pea sized ball of bee's wax and sheep tallow lube (a 50/50 mix) for a "lube cookie" in each chamber (between powder and ball),.... and .454 round balls (which I cast), I also have a Lee conical mold but never have taken the time to cast any of those.
2 of my Piettas have 8" barrels and the 3rd. has a 5 1/2" barrel.
I also lube the cylinder pin with the same lube as I use for the "lube cookies".
I've never had a chain-fire, and I have several cylinders for each pistol, which are carried (loaded) in cylinder pouches on each belt and holster set-up.
The Traditions cylinder loading tool is kind'a flimsy, but cheap and will work for a while,.... but something like the "tower-of-power" cylinder loading tool will last for generations.
Sorry I can't help with the cartridge cylinder conversions, I've never bothered getting one 'cause I'm still having too much with the percussion cylinders.