Slug your barrel first before you decide what size to size your bullets. I get good performance out of my .428 bullets in my .427 and .429 bores because my bullets are dead soft, pure lead. They bump up in the bore to fill the .429 rifling. I was using .427 bullets for all my rifles until I bought my Henry, which has the .429 groove diameter. That's why I compromised on .428.
With most modern Uberti 44-40 rifles you are going to find the groove diameter is .429. Standard lead bullet logic says to use a bullet .001 over groove diameter, or .430. However......................Uberti chambers can be tight. If using a .430 bullet in a tight chamber you might find that the bullet expands the case mouth enough that the rounds are stubborn to chamber. For example, my old Uberti 1873 with its .427 groove diameter will shoot .427, .428, and .429 bullets just fine. However rounds loaded with .429 bullets can be a bit ornery to chamber because of the tight chamber. That is why I always used to go with Winchester 44-40 brass; it has the thinnest brass at the neck of any other brand, right about .007. Starline is pretty thin too. If one uses a brand of brass that is a tad thicker at the mouth, just a thou or so, with a 'large diameter bullet' like .429 or .430, that can result in a round that is stubborn to chamber. The thinnest brass is the most forgiving if you need to use 'large diameter bullets'.
Slug your bore, then make an informed decision about what diameter to size your bullets. If they are cheap enough, it might not hurt to buy a couple of different diameter sizing dies.