I don't have a Paterson, so I can't help with that one, but...
I do have a Uberti Walker. Yes, the nipple threads are 1/4x28. As for the Treso part number I believe the 11-50-01 is a better choice. The OEM nipples on my gun are rather tall, 0.627" overall (including the threaded portion). The 11-50-13 Treso nipple is just 0.538" tall overall, with a cone height of 0.327". The 11-50-01 is a better height match at 0.635" overall with a cone height of 0.433".
The important dimension is the cone height, of course, and I don't have that number for the Uberti OEM nipple, but the 11-50-01 is much more likely to be correct. The difference between the two Tresos is rather substantial (0.106"), almost all of it in the cone.