This combination is used relatively frequently in qualitative Health Psychology. I would start off with this paper by Sue Wilkinson (Article Focus Groups in Health Research: Exploring the Meanings of H...
A lot depends on what you mean by "narrative analysis," since their are several versions of this technique. But all of they share an interest in stories and story telling, which you can definitely hear in focus groups.
There are interesting studies being done by Manchester Metropolitan University on linguistics. Rob Drummond is on Twitter, you might want to contact him for some advice if you've not already spoken to him, and also Vijay Ramjattan.
I agree with Marion Todd and Annika Hamachers. Their comments are useful. In addition, David L Morgan lifted up good points about different ways to use narrative analysis. In narrative analysis, it is possible to focus on the content of narratives or on the form of narratives. In the latter, you can consider the different ways people are telling narraives.