You didn't mention length of barrel, Walt or gun design.
I would say a 1", .54 at 42" straight octagonal might be too heavy for some people, however a 34" X 1" X .54 would be perfect for a 1/2 stocked nrifle. In the first example, the 15/16" (in flint only) might be better for most people, whereas in the second, the 15/16" would be too light - for me
I'm the little 235 pounder in the green parka, (group picture) that Taylor posted of our shooting yesterday.
A patent breech 15/16" .54 would probably be just fine.