Mark,
Interesting specs on your bow, #113~7, 64", #50@28". Can you post a photograph of it?
The Roper Bighorn was made by Lowell W. Roper, a well known California bowmen who manufactured a few very unusual archery items in during the 1950s. Roper was the 1956 NFAA National Champion in the Broadhead Head Round.
I never knew Roper, but talked with old bowmen who did know him and by all accounts he was a character. Apparently, no one was ever certain when he was serious.
Roper applied for a patent for a bow in 1955 and in 1958 was granted a patent for it. His Roper's Indian Arrowhead was also patented. It is an unusual fluted design broadhead that was commercially produced and is well documented in patented illustrations, advertisements and the most comprehensive books on the subject.