In that case, I would recommend using the QtQuick Quickly template that's currently in development.
With it, you'll be able to use Quickly with PySide (and QML) as you're intending to do.
Note that this template is still in development and is thus not yet part of the Quickly core set of templates, so use it at your own risk and do not expect everything to work.
That said, last time I tried it, it worked quite well, and had no issues at all with it.
Here's how to install it, simply run this command on a terminal to install it from the daily PPA:
sudo add-apt-repository ppa:quickly-templates-hackers/quickly-community-templates-daily
Then install it:
sudo apt-get update && sudo apt-get install quickly-ubuntu-application-qt-template
Once installed, you can create a QtQuick application with the following command:
quickly create ubuntu-qtquick-application <yourappname>
You can also create a pure Qt app with the Qt template:
quickly create ubuntu-qt-application <yourappname>
If you find any bugs with the template, we'd appreciate it if you would report them, which would help us make it better for you and everyone else using it.