the simplest way would be to use a webhook to recompute the actual date or the 65th anniversary date and store it in another field. Look into the lauchpoint to find some webhook platforms. Some have a free version that should be enough for your needs.
Once you have this date, setting up the smart campaign will be very easy. Just use "65th Anniversary in past month" or "in next month".
there are several threads in which you describe this in more detail.