General ...
I started a search in my hopelessly disorganized stashes of stuff, but stopped when I remembered that the belt/bandolier I have (or had) was for .303 size cartridges ... or at least that is what I tried to use it for, without success, as it may actually have been a.45-70 item which I got it to try to use for .303 rounds It was a relatively inexpensive one I bought from somewhere - maybe Coon Creek (?)
(However, it has also occurred to me that I may in fact have brought it as a door prize to a past Muster.)
In any event, as I recall, .303 cases were definitley too loose in the loops, so I quit using it. Even if the existing loops wouldn't take .45-70 ... they are sewn, and since quite a few of them would need to be unstitched for your project, anyway the others could likely also be taken out and resized to the correct diameter.
Say the word, if interested, and I'll keep looking ... ( The price would be right, if I still have it ...)