I don't think aspect ratio - 16:9 versus 4:3 will have any effect on disc capacity.

Even if your 1 hr 55min program is standard definition and not HD I don't think you will get it to fit on a single layer disc - depends on size of your source video files.

I can usually get about 3.8gig of content on a 4.7gig single layer sized disc and have room for the added program space required for transcoding it to dvd with chapter menus and etc.

If your program won't quite fit remember you can always use something like DVDShrink to do the extra compression to allow it to fit. DVDShink can still be found around the web as a free download. shrink is a great little utility but requires the Nero burn engine to function. Do you have Nero?
goodluck