Aspirin I haven't taken aspirin in over 40 years, I wasn't allergic to it but would like to take it now. I am 65. I am assuming if I didn't have an allergic reaction when young, I won't now?

In short, most likel. There are no real good clinical tests, (e.g. In vitro), and the best test is a challenge to the drug, oral, in a controlled setting, e.g. Doctor's office. But you prob dont have one since your history indicates that you never had a reaction.
There . There is no reason to believe you will have a problem unless you've had a reaction to a related drug such Ibuprofen in the past.