personally I don't know of anybody that makes oversized nipples.
Although a sae thread nipple may be a bit bigger than the metric.
But you also need to consider the overall height of the nipple.
Best bet take it to machine shop, or gun smith have them install a helicoil restoring
it to original threads.
Or buy a new cylinder
This is another reason to remove the nipples once, coat with antisieze reinstall and then remove only once every few years.
You don't have to remove the nipples to make sure they are clean.
I haven'tremoved the nipples on my guns in 5 yr, but yet I know they will come out because of the coating, they always have in the past.