In a job talk for a postdoc position, should I refocus my talk to be closer to the research at this research center?
No. Having given these talks (and attended a great many of them) in the past, I can say from experience that most likely the research center wants to know how you present work in general, and if you can speak to a wide audience. 

If you want to tailor the your talk at all, make sure it is providing sufficient background and give a "big-picture" version of your work. It is fine to include details (indeed that is expected), but don't get your self hung up on minuscule details related to your methods (unless asked). 

Best of luck.