It sounds like you're using the 720p projector as a computer monitor in effect right? If so,this usually comes down to an issue between your computer, your graphics card and your GPU drivers. Many times if you go into your display settings, you can switch the output resolutions. For example, you said your projector is a 720p projector but your maximum resolution you're getting now is 664 - something is amiss there.
- update your GPU drivers (nvidia or ATI)
- noodle with your display settings to get above the resolution you're currently getting
- resize the Premiere application to make it fit within whatever final resolution you get from your computer/projector.
Hope this helps,
The preview of the video in premiere cut off on all sides about 10-15%.
Set the Program Monitor resolution to Fit.