Yeah, "Classic Builder", that's what it was called!
In our implementation, I created a separate "Unbounce" property in Launch, so that I could set up hard coded values specific to "unbounce" (similar to what you need, so that we could separate out these pages from our main site).
I also read some of the information directly from the Unbounce objects on the page.. in the window.ub object. For me, these always were available before my tracking fired... (and believe me, I've had to deal with other timing issues in some of our implementations).
If you really want to use the same property from your website onto your Unbounce pages, you can... but depending on your implementation, this could make it harder to manage and test new changes when its not isolated... I personally like to create a Launch property per "code base", so that I don't have to do a lot of checks and balances to determine which is which... each Launch property can still send to the same tracking suite, it just allows you to make different logic, or "lock" specific values where you need them.
