Today I came across a large number of letters from Ong to his parents, written between the years 1947 and 1956, essentially the time from when he went East to Harvard until his mother died (his father died in 1954). This includes the entire time he was in Europe doing his dissertation research. There's also much smaller files for both of his parents. The file for his mother includes her Rosary. That is most definitely going on display in the exhibit.
In a letter to his parents, dated Oct. 29, 1954, written from Etudes -- the Jesuit residence in Paris which Ong used as a home base for much of his time while doing dissertation research in Europe, he writes:
"It wasn't De Mille's Queen of Queens, which I guess will be pretty horrible, but Samson and Delilah that I had to do with. You should see the film if you get a chance, S&D I mean, not that it's much worth while...but because I had something to do with it -- not so much with the lines that are in it as those that aren't.... The S&D scripts was sent to me all through its development, in its various stages of evolution, which might be described as from worse to bad. Them's Phil's sentiments, too."