I agree. Political economy is sufficiently broad that increased specificity will improve your "fit" argument. Even if you focus solely on IPE and ignore the comparative literature (comparative capitalisms, political economy of specific regions, welfare state, economic sociology, etc), you still have a array of topics to deal with (trade, development, monetary politics, economic coercion and sanctions, cooperation, globalization, regional integration, institutions, etc).
Granted, this won't always be possible and you might need to make more general arguments regarding fit.