Your research interests sound cool and I'm sure you'd be fine in a sociology program. Although, I may be a bit biased since I am also interested in the persistence of free market (and alternative) development models, but in Latin America.
Also, political economy is an inherently interdisciplinary field no matter what discipline one is in--sociology, political science, economics, or history. I actually find myself citing political scientists and economists as often as I cite sociologists. In my opinion, having a poli sci background and being quantitative would make you more marketable. You should be able to benefit from attending conferences and making connections in both fields (e.g. both ASA and APSA).
What sociology program are you waitlisted for?