Andrew, your rose has the habit of a hybrid tea. Belle Helene is a Gallica. It blooms only once a year and it's relatively thornless (it has only a few small thorns on each cane). Queen Elizabeth is the right color, but it doesn't have as many petals as your rose.
I found my guesses by looking for pink hybrid teas with large blooms with more than 40 petals.
Frillylily, you're wrong to say there's a good chance it isn't grafted. Own-root roses were not being sold 50 years ago. They were present in gardens, of course, but only if the gardener had grown them himself from cuttings. All nursery-grown roses, even landscape shrubs and OGRs were grafted then. The own-root rose nursery is a relatively new phenomenon.
