There is nothing wrong with the paper being old.
As an example, I once did a live experiment during a conference, with the attending people as participants in the experiment. Obviously, I couldn't evaluate and write up the data during the conference, although I had to give a talk with first results 24 hours after the experiment. I was also required to submit a paper with the complete results with the postproceedings, and these postproceedings appeared maybe 4 months after the conference and were sent to everybody who attended it that year.
I had to give the talk on the postproceedings paper the following year, when the conference was held again. Of course, it was attended by the same crowd of known faces (it is a conference for a somewhat small community). These were the same people who had heard the first results the year before, and then received the written paper.
Still, the talk was a success. The audience was very attentive during the talk, and I received both really good questions and great positive feedback afterwards, having professors come up to me, an unknown doctoral student, and express interest and praise for my work. They weren't bored at the "old news".
In fact, I don't think they had read the paper from the postproceedings, and that's fine. With the sheer quantity of research produced these days, nobody can keep up with all publications in their core area, and everybody picks only the stuff which has direct implication for their own work. They are still very interested in related topics when they get the occasion to hear about them, and enjoy good work. They just don't seek this information actively.
So, give the talk. It is a way to promote yourself and your work, and also your area X, which can have interesting synergies with Y. I doubt that anybody will have a negative reaction just because the paper has been sitting around for months.