1080p - 720p

Hello, OK so..

I'm making a frag movie compilation (clips from the video game) some where recorded at 1680x1050 and some where recorded at 1920x1080. I began a new project @ 1080p, however, the first video I inserted was 1680x1050, and I selected to change the base resolution or whatever the option says that comes up, so basically the entire video is set at the resolution of 1680x1050, upon trying to render, if I select 1080p, there are black bars on all four sides of most of the videos, and then black bars on the left and right of the other videos.. If I try to render at 720p, same thing but lower quality seemingly.

I've spent 4 days creating this video, approximately 20-30 hrs work, and I realllllly don't want to have to start again, I'm praying there's a way to change the video settings or something so that the default resolution is 1080p and then the 1680x1050 clips have the bars and/or are stretched, that's fine, there's less of them, there's more 1080p clips.

I hope that makes sense, I'm wanting to export in 1080p HD for YouTube, and currently the entire video consists of a lot of black bars all around the videos, and when viewing it, you're thinking to yourself, "why wouldn't the creator put them at full resolution.." !

- Adobe Premiere Pro CS6

Thanks in advance, PLEASEeeeeeeeeeeee give good news haha