I am not in the STEM fields, but perhaps the overview talk would be fine, with being very prepared to answer more in-depth questions about either topic? What type of university are you interviewing with?
Follow-up to original post:
The research talk went fine, there was one question about the research that I flat-out could not answer, but I am trying not to stress too much about it....
I hope so, because the abstract I just sent off is for the overview talk. That was the way it worked last time - it seemed to go over well, and I got good questions about both topics, but I'm still waiting for the decision from that place, so who knows. This university is a public master's granting place, so not R1 or anything, but they are definitely into research, and asked a lot about it in the phone interview.
Anyway, glad that your talk went well, and at least you can make sure to be prepared for that sort of question next time.