I haven't made the repository public yet. This app has started has a by product of a game I was working on, and as such it's code is overcomplicated. I've wanted to clean it, for some time now.
In the meantime, if you open the pak file (it's just a zip) you can see how things are organized.
Look at the race files. They define what parts are used for each body.
Then look at the gear files. One of the fields of each gear definition is what body/head they can work with.
Hope this helps for now.