[showtime89]

Ok, I have an ongoing project. I completed it once on a DL DVD but due to the size I only got compressed video and 2 channel Audio. I would like Video plus DD 5.1 like the sources have. Here's the deal.

I am combining and editing 3 DVD movies into one DVD movie. End project is about 5.5 hrs long. Like I stated above, I did this with a Dual Layer DVD and with some video and audio compression I ended up with a decent video, with only 2 channel audio, because it was just too much to put on the disc. Well, enter Blu-ray with 25gb capacity and I think I can pull this off.
I have the 3 DVD's ripped to the HD in .m2v/.ac3 format so I can import them, but by the time I imported all 3 movies, I was way over the BD disc capacity(49GB over the 25 GB capacity). All 3 movies only take up 14.2gb on my HD, so I was figuring that it would be that or less once I was done cutting and editing the movies before I work the menus in and such, leaving at least 10GB of space on the disc. How can I import them while maintaining original Video quality and 5.1 Audio and then combine them so I can output to a single Blu-Ray disc? I know I can change transcoding settings, but what would be ideal to maintain the original product?

Thanks in advance for any help.