Ok, that sounds about right, the large ring is 1.10" With 12 threads per inch, and the small ring is .980" With 12 threads per inch. Is your Peruvian the long action or the intermediate length?
Mine is the intermediate length but it is still 1.10" 12tpi, make sure they sent you the right thread, find someone that has a thread gauge and check the action and the barrel.
Greg